강섬유 보강 콘크리트(Steel Fiber Reinforced Concrete, SFRC)는 콘크리트의 취성적인 거동을 연성 거동으로 보완해주는 재료로서 사용되고 있다. SFRC는 과거 비 구조체에서 섬유 보강 콘크리트는 균 열을 제어하기 위한 목적으로만 사용되었지만 현재 구조적인 재료로서의 연구가 진행되고 있다. 콘크 리트의 압축강도는 강도계산에 사용되지만 재료의 인성(Toughness)을 평가하기 위해서는 응력-변형률 곡선이 필요하다. 본 연구에서는 섬유의 혼입량을 체적비 0.5%로 두어 나선철근의 유무 및 철근의 피 치를 변수로 두어 압축실험을 통해 인성비(Toughness Ratio)를 측정하였으며, 선행연구에 제안된 예측 식을 통해 실험 값과 해석 값을 비교하였다. 사용한 강섬유는 직경 0.75mm, 길이 60mm 및 인장강도 1,100MPa인 후크형 모양의 섬유를 사용하였으며, SFRC의 압축 실험은 200tonf 용량의 UTM을 사용 하여 응력-변형률 곡선을 확인하기 위해 0.5mm/min의 속도로 변위제어 하였다. Plain 시편의 압축강 도는 19.6MPa로 나타났으며, 52mm간격의 나선철근을 넣은 경우 33.3MPa, 섬유 0.5% 혼입한 경우 29MPa로 각각 70.1% 및 48.0% 높은 압축강도가 나타났다. 52mm 간격의 나선철근을 넣은 시편의 인성비는 0.34로 측정되었으며, 0.5%의 섬유가 혼입된 52mm 및 36mm간격으로 보강된 시편의 경우 각 0.32 및 0.49로 -6.5% 및 44.3%의 증감이 나타났다. 따라서 섬유의 보강으로 인한 SFRC의 인성 거동을 확인하였다. 예측식의 경우 52mm 나선철근으로 보강한 시편의 경우 압축강도 -0.06 및 변형 률 -7.37%의 오차율이 나타났으며, 36mm의 경우 각 11.51% 및 -36.5%의 오차율이 나타났다. 따라 서 예측식을 통해 나선철근으로 보강된 SFRC 강도예측을 확인하였다.

The heat transfer characteristics of double-pipe spiral heat exchanger were investigated by various curvature sizes, experimentally. The three different sizes of heat exchanger were made and tested with water as a working fluid to analyze the heat transfer characteristics. The heat transfer rates, overall heat transfer coefficient and pressure drop were analyzed with various heat exchanger sizes (i.e., curvature ratios). As result, the heat transfer rate increased with increasing the size of the heat exchanger as the flow rate increased due to increasing the area size of heat transfer. However, the overall heat transfer coefficient and pressure drop increased with decreasing the heat exchanger size (i.e., increased curvature ratio) due to the enhanced centrifugal force and inertia.

A spiral flow path was applied to solve the problem of the existing straight flow path in the leveling shaft, a key component of the self-levelizer that can maintain the height according to the change in payload in EV, SUV. In this study, flow analysis was performed to check the velocity, pressure drop, and flow direction of oil according to the main operating conditions of the leveling shaft with a spiral flow path. As a result of the study, a leveling shaft with a spiral flow path is likely to improve fluid properties around the orifice and inlet valve under compression conditions, and it is judged to have a development application effect.

The propagation speed of a circumstellar pattern revealed in the plane of the sky is often assumed to represent the expansion speed of the wind matter ejected from a post-main-sequence star at the center. We point out that the often-adopted isotropic wind assumption and the binary hypothesis as the underlying origin for the circumstellar pattern in the shape of multilayered shells are, however, mutually incompatible. We revisit the hydrodynamic models for spiral-shell patterns induced by the orbital motion of a hypothesized binary, of which one star is losing mass at a high rate. The distributions of transverse wind velocities as a function of position angle in the plane of the sky are explored along viewing directions. The variation of the transverse wind velocity is as large as half the average wind velocity over the entire three dimensional domain in the simulated models investigated in this work. The directional dependence of the wind velocity is indicative of the overall morphology of the circumstellar material, implying that kinematic information is an important ingredient in modeling the snapshot monitoring (often in the optical and near-infrared) or the spectral imaging observations for molecular line emissions.

Background: Previous studies have reported that improving the spinal stability could be more effective in the prevention and treatment of recurrence. Lumbar stabilization exercise is known to strengthen the lumbar extension muscles and enhance physical, psychological and social functions. Objectives: To investigated the effect of lumbar spiral stenosis on the kinetic link training and lumbar stabilization exercise. Design: A randomized controlled trial. Methods: Study was preformed by randomly allocated 28 LSS participants into a kinetic link training group (KLT, n=14) and a lumbar stabilization exercise group (LSE, n=14). Kinetic link training and lumbar stabilization exercise were performed to subjects in both groups 5 times a week for 6 weeks. To verify the effect of LSS, changes in VAS, ODI, and proprioception before and after intervention were observed. Results: In KLT, statistically significant changes were found in VAS, ODI, and Proprioception before and after intervention. In LSE, there were significant changes in VAS and ODI before and after intervention. KLT and LSE before and after intervention indicated significant differences in proprioception. Conclusion: KLT and LSE are applied to LSS, there are effects of pain decrease, lumbar recovery and proprioception improvement.

Recently, the demand for reliability verification is increasing while designing and manufacturing molds using injection molding computer aided engineering(CAE). When performing flow analysis verification, a spiral mold is produced and compared with CAE. Because of the spiral shape, we needed a comparative evaluation with the flow distance of products with different forms. So, we compared the weight and flowed length using CAE. Variables are the change in the width of the spiral shape and the shape of the bar and plate. When the width of the spiral shape is 23mm rather than 15mm, the flow distance flows 30∼70mm more, with a maximum difference of 13%. As a result of comparing the spiral shape and the long square shape with the same width, the spiral shape had a flow distance of 60 to 105mm further, and a difference of up to 28% was found. As a result of comparing the plate shape and the spiral shape with a 15mm width product, the spiral shape has a flow distance of 310∼380mm further, and a difference of up to 82% is different.

본 논문은 철계형상기억합금(Fe-SMA) 나선철근을 이용한 기둥의 횡구속 효과를 평가한 실험적 연구를 보고한다. 실험을 위해 사전변형 4%의 5mm × 5mm의 Fe-SMA 나선철근으로 구속된 150mm × 150mm ×300mm의 원형 실험체가 제작되었다. 실험변수는 Fe-SMA 나선철근의 피치(0mm, 80mm, 60mm, 40mm), Fe-SMA 나선철근의 활성화 유무(활성화, 비활성화)를 고려하였다. Fe-SMA 나선철근 활성화를 위해 소성로를 사용하여 목표온도 140℃까지 가열하였다. 실험체의 온도가 상온에 도달한 후 만능재료시험기를 이용하여 1축 압축실험을 실시하였다. 실험결과를 통해 Fe-SMA 나선철근을 활성화하여 능동적 횡구속압이 작용된 실험체의 최대응력과 최대응력 발현 시의 변형률은 활성화하지 않은 실험체에 비해 크게 증가하는 것으로 나타났다. 또한, 나선철근 피치의 감소로 인해 능동적 구속압이 증가함에 따라 최대응력과 연성지수가 크게 증가하는 것으로 나타났다. 특히 보강 간격이 40mm인 활성화된 나선철근으로 구속된 실험체는 최대하중 도달 후 하중이 유지 및 증가하는 변형경화가 발생하는 것으로 나타났다.

We developed a wet scrubber by applying cyclone flow to the gas flow and using a spiral filter structure. While the size of a new scrubber was about half that of a conventional scrubber, the device showed relatively high efficiency in pollutants removal such as particulate matter and compounds inducing odor. The new scrubber installed in a plating industry showed a higher removal efficiency of about 5% for dust, about 23% for hydrogen chloride, and about 23% for sulfur dioxide compared to the conventional scrubber. Plurality of tubes in the spiral filer housing are arranged to be vertically shifted from each other. Because the upward residual gas does not directly rise vertically, the residence time of gas between the filter plates is extended. Thus, the purification efficiency of the pollutants was enhanced in the new scrubber. In addition, the new scrubber developed in this study is more cost effective because the cost saving in manufacturing it compared with a conventional scrubber increases with increasing the size of equipment. It is expected that a scrubber with better dust collecting efficiency can be obtained by carrying out a study in connection with facilities capable of controlling acidity of washing water.