• 대한정형도수물리치료학회지
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• 제28권1호
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• pp.1-7
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• 2022

Purpose: The purpose of this study is to examine the unstable wall squat exercise and stable bridge exercise on posture in normal adults. Methods: The subjects of this study were 34 university students who were normal health adults, equally and randomly allocated to a unstable wall squat exercise group (male 7, female 10), an experimental group, and a stable bridge exercise group, a control group. Both did so for 30 minutes three times per week over a six-weeks period. Using Back Mapper, their trunk inclination (TIN), trunk imbalance (TIM), pelvic position (PPO), pelvic torsion (PTO), pelvic rotation (PRO) and the position of their scapula (PSA) were evaluated. Results: When the pre-test and post-test results of experimental group and control group were compared, statistically significant differences in TIN, PTO and PSA of experimental group were seen. Conclusion: Unstable wall squat exercise accompanied by abdominal drawing-in may be applied as a method to correct the posture in normal adults.

• 한국지반신소재학회논문집
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• 제12권1호
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• pp.101-107
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• 2013

최근 들어 토목 구조물에도 친환경성과 경제성이 강조되고 있으며 콘크리트 블록대신 soilbag을 전면벽으로 이용하는 절토사면 보강공법이 활용되고 있다. 그러나 친환경적이고 경제적인 재료라 하더라도 안정성이 보장되지 않으면 구조물로써의 가치를 지닐 수 없다. Soilbag 옹벽의 안전성 검토를 위해 기존의 옹벽 설계프로그램인 MSEW를 사용하여 연결부에서의 인발저항, 파단, 인장응력과 내적, 외적 안전율을 산정하고 블록식 보강토 옹벽의 안전율 산정결과와 비교하였다. 연결부의 안전성을 평가할 수 있는 연결강도 감소계수를 차등 적용시켜 연결강도가 감소함에 따라 옹벽의 안전율을 검토하였고 soilbag 보강토 옹벽에서는 soilbag과 지오그리드 보강재의 연결재가 이동이 가능하기 때문에 전면구배의 변경이 자유로우므로 soilbag의 구배에 따른 안전율 변화도 확인하였다. 해석결과로부터 soilbag을 이용한 보강토 옹벽의 연결부 강도에 대한 안전율 및 내적, 외적안정에 대한 안전율을 비교 검토한 결과 전 영역에서 기준 안전율 이상임을 나타내었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.504-507
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• 2011

The inertial migration of a two-dimensional elastic capsule in a channel flow was studied over the Reynolds number range $1{\leq}Re{\leq}100$. The lateral migration velocity, slip velocity, and the deformation and inclination angle of the capsule were investigated by varying the lateral position, Reynolds number, capsule-to-channel size ratio(${\lambda}$), membrane stretching coefficient(${\Phi}$), and membrane bending coefficient(${\gamma}$). During the initial transient motion, the lateral migration velocity increased with increasing Re and ${\lambda}$ but decreased with increases in ${\Phi}$, ${\gamma}$ and the lateral distance from the wall. The initial behavior of the capsule was influenced by variation in the initial lateral position ($y_0$), but the equilibrium position of the capsule was not affected by such variation. The balance between the wall effect and the shear gradient effect determined the equilibrium position. As Re increased, the equilibrium position initially shifted closer to the wall and then moved towards the channel center. A peak in the equilibrium position was observed near Re=30 for ${\gamma}=0.1$, and the peak shifted to higher Re as ${\gamma}$ increased. Depending on the lateral migration velocity, the equilibrium position moved toward the centerline for larger ${\gamma}$ but moved toward the wall for larger ${\Phi}$ and ${\gamma}$.

• 산업기술연구
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• 제18권
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• pp.405-415
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• 1998

This thesis is an experimental and numerical research on bearing capacity acting retaining walls close to rigid slopes with stiff angles. Experiments were performed with changing the roughness of adjacent slope to the wall, its inclination, distance between wall and slope. Vertical stress and applied surcharge loads were measured by miniature earth cells and a load cel respectively. Stress distribution Vertical Settlement of surcharge load of rigid model footing were measured by LVDTs. Bearing capacities of surcharge loads were compared with theoretical estimations by using several different methods of limit equilibrium and numerical analysis. For limit equilibrium methods, the modified silo and the wedge theories, proposed by Chung sung gyo and Chung in gyo (1994) were used to analyze test results Based on those modified theories, the particular solution with the boundary condition of surcharge loads on the surface of backfill was obtained to find the stress distributions acting in the backfill and to compare with test results. From results of surcharge test with model wall being very close to the slope, analyzed results by the modified silo theory and to be in the better agreements than other methods.

• 항공우주기술
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• 제2권2호
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• pp.18-24
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• 2003

비행선의 자세각 변화는 내부의 헬륨 가스의 쏠림에 의한 부력중심 이동을 수반하게 된다. 본 논문에서는 자세각에 따른 부력중심 이동거리를 산출하고, 그에 따른 정적 종안 정성을 고찰하였다. 또한, 부력중심 이동 거리를 줄이기 위하여 비행선 내부에 설치된 격막에 의한 효과를 검토하였다. 부력중심은 정적 종안정성을 저하시키는 방향으로 이동하므로, 현 설계에서는 격막의 설치가 필수적이다. 속도에 대한 종적 정안정성을 고찰한 결과, 현 설계에서는 매우 낮은 속도 영역에서 정적으로 안정함을 알 수 있다.

• 동력기계공학회지
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• 제18권2호
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• pp.12-18
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• 2014

The local heat transfer of developed turbulent flows in the stationary ribbed rectangular convergent channels has been investigated experimentally. The rectangular convergent channels with one ribbed surface only have the inclination of $0.72^{\circ}$ and $1.43^{\circ}$ at which the ribbed wall is manufactured with a fixed rib height (e) of 10 mm and the ratio of rib spacing (p) to height (e) =10. The measurement was conducted within the range of Reynolds numbers from 15,000 to 89,000. The local heat transfer characteristics of the rectangular convergent channels are quite different from those of the ribbed square straight channel.

• 대한기계학회논문집B
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• 제21권5호
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• pp.628-636
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• 1997

Flow visualization technique incorporating photochromic dye is used to study the flow characteristics of the gravity driven laminar wavy film. The film thickness and wave speed are successfully measured by flow visualization. As the inclination angle increases, the waves have higher peaks and lower substrate thickness. The measured cross stream velocity at the free surface is up to 10% of stream wise velocity, which shows enhanced mixing in the lump of the film. The measured stream wise velocity profiles are close to parabolic profile near the substrate and the peak but show significant velocity defect near the rear side of the wave. The measured wall shear rate distributions show good agreement with the previous workers' numerical results.

• 대한기계학회논문집B
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• 제32권3호
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• pp.198-206
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• 2008

A numerical study has been carried out to investigate heat transfer enhancement in channel flow using large-scale vortices. A square cylinder, inclined with respect to the main flow direction, is located at the center of the channel flow, generating a separation region and Karman vortices. Two cases are considered; one with a fixed blockage ratio and the other one with a fixed cylinder size. In both cases, the flow characteristics downstream of the cylinder significantly change depending on the inclination angle. As a result, heat transfer from channel wall is significantly enhanced due to increased vertical-velocity fluctuations induced by the large-scale vortices shed from the cylinder. Quantitative results as well as qualitative physical explanation are presented to justify the effectiveness of the inclined square cylinder as a vortex generator to enhance heat transfer from channel wall.

• Journal of Plant Biology
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• 제26권1호
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• pp.7-16
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• 1983

Internodal vessel elements are studied in 20 genera, 75 species and 33 cultivars of Hibiscus rosa-sinensis belong to the Malvaceae. The minimum and maximum length and diameter range from 79~466 and 14~88 ${\mu}{\textrm}{m}$, respectively. The vessel elements are either cylindrical, fusiform, conical, clavate, oval, column-, drum-, fish and cup-like or erratic. Perforation plates are exclusively simple in all the species investigated, except occasionally scalariform in varieties of Hibiscus rosa-sinensis. In most of the species studied vessel elements have predominantly two perforation plates or occasionally one and three. Adjacen side wall thickening is commonly simple and border pitted, mixed, scalariform, helical and reticulate. The vessel elements vary in their size, shape, number and inclination of perforation plates and adjacent wall thickening.

• 대한기계학회논문집B
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• 제21권11호
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• pp.1496-1508
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• 1997

The effects of porous wind fence on the pressure characteristics around a 2-dimensional prism model of triangular cross-section were investigated experimentally. The fence and prism model were embedded in a neutral atmospheric surface boundary layer over the city suburb. In this study, various fences of different porosity, back fence, inclination angle of prism and location of additional back prisms were tested to investigate their effects on the pressure and wall shear stress of the prism surface. The fence and prism had the same height of 40 mm and Reynolds number based on the model height was Re=3.9*10$^{4}$. The porous fence with porosity 40% was found to be the best wind fence for decreasing the mean and pressure fluctuations on the prism surface. By installing the fence of porosity 40%, the wall shear stress on the windward surface of prism was largely decreased up to 1/3 of that without the fence. This indicates that the porous fence is most effective to abate the wind erosion. Pressure fluctuations on the model surface were decreased more than half when a back fence was located behind the prism in addition to the front fence. With locating several back prisms and decreasing the inclination angle of triangular prism, the pressure fluctuations on the model surface were increased on the contrary.