• Title/Summary/Keyword: Compound Tubes

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ENERGY ABSORPTION CHARACTERISTICS IN SQUARE OR CIRCULAR SHAPED ALUMINUM/CFRP COMPOUND TUBES UNDER AXIAL COMPRESSION

  • CHA C. S.;LEE K. S.;CHUNG J. O.;MIN H. K.;PYEON S. B.;YANG I. Y.
    • International Journal of Automotive Technology
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    • v.6 no.5
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    • pp.501-506
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    • 2005
  • With the respective collapse characteristics of aluminum and CFRP (Carbon Fiber Reinforced Plastics) tubes in mind, axial collapse tests were performed for aluminum/CFRP compound tubes, which are composed of square or circular shaped aluminum tubes wrapped with CFRP outside. In this study, the collapse modes and the energy absorption characteristics were analyzed for aluminum/CFRP compound tubes which have different fiber orientation angle of CFRP. Fracture modes in the aluminum/CFRP compound tubes were rather stable than those in the CFRP tubes alone, probably due to the ductile nature of the inner aluminum tubes. The absorbed energy per unit volume of the aluminum or the aluminum/CFRP compound tubes was higher than that of CFRP tubes. Meanwhile, the absorbed energy per unit mass, for the light-weight design aspect was higher in the aluminum/CFRP compound tubes than in the aluminum tubes or the CFRP tubes. The energy absorption turned out to be higher in circular tubes than in square tubes. Beside the collapse modes and the energy absorption characteristics were influenced by the orientation angle, and the compound tubes took the most effective energy absorption when the fiber orientation angle of CFRP was 90 degrees.

Energy Absorption Characteristics of Al/CFRP Compound Tubes Under Axial Compression (축 하중을 받는 AI/CFRP 혼성튜브의 에너지흡수 특성)

  • 이길성;차천석;문지현;양인영
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.10a
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    • pp.108-113
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    • 2004
  • The compressive axial collapse tests were performed to investigate energy absorption characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP (Carbon Fiber Reinforced Plastics) outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different fiber orientation angles. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, specific energy absorption were the highest for Al/CFRP, CFRP in the middle, and aluminum the lowest. Also, specific energy absorption of circular tubes was higher than square tubes'. It turned out that fiber orientation angle of Al/CFRP compound tubes influence specific energy absorption together with the collapse modes of the tubes.

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A Study on the Collapse Modes and Energy Absorption Characteristics of AI/CFRP Compound Tubes Under Axial Compression (축 하중을 받는 Al/CFRP 혼성튜브의 압궤모드와 에너지흡수 특성에 관한 연구)

  • Cha, Cheon-Seok;Lee, Kil-Sung;Chung, Jin-Oh;Yang, In-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.11
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    • pp.1768-1775
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    • 2004
  • The compressive axial collapse tests were performed to investigate collapse modes and energy absorption characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP(Carbon Fiber Reinforced Plastics) outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different CFRP orientation angles. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, specific energy absorption were the highest for Al/CFRP, CFRP in the middle, and aluminum the lowest. Also, specific energy absorption of circular tubes was higher than square tubes'. It turned out that CFRP orientation angle of Al/CFRP compound tubes influence specific energy absorption together with the collapse modes of the tubes.

Characteristics of Heat Transfer and Pressure Drop for Spirally Indented Tubes with Wire Coil Inserts (와이어 코일이 삽입된 나선형 내면가공관의 열전달 및 압력강하 특성)

  • Choi, In-Su;Park, Byung-Duck;Nam, Sang-Chul
    • Journal of the Korean Society of Industry Convergence
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    • v.4 no.4
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    • pp.395-401
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    • 2001
  • The characteristics of heat transfer and pressure drop through tubes has been investigated experimentally for a compound heat transfer enhancement. The test tubes were spirally indented tubes with wire coil inserts which had a various combinations of pitch and helix angles. Pure water was used as working fluids for the experiments, Heat transfer coefficients and friction factors of the test tubes were evaluated from the values of measured temperatures, flow rates and pressure drops. An performance evaluation was performed to find an optimal combination of spirally indented tubes with wire coil inserts. When the helix angle of wire coil insert are $71^{\circ}-72^{\circ}$, the best heat transfer enhancement was shown. The friction factor was 9 - 13 times higher than those in smooth tubes, and the heat transfer was enhanced a maximum of 500%.

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Experimental Study for Nerve Regeneration Using Tubes Filled with Autogenous Skeletal Muscle in a Gap of Rabbit Sciatic Nerves (백색 가토 좌골 신경의 신경 결손부위에서 자가 골격근 충진 도관을 이용한 신경재생 연구)

  • Lee, Jun-Mo;Shin, Sung-Jin;Seo, Jeong-Hwan;Song, Chang-Ho
    • Archives of Reconstructive Microsurgery
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    • v.12 no.1
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    • pp.1-12
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    • 2003
  • The bridging of nerve gaps is still one of the major problems in peripheral nerve surgery. To evaluate the role of silicon tube in nerve regeneration, gaps were made by resection of tibial components of sciatic nerves of twenty-five New Zealand rabbits. The gaps were divided into five groups. In group I, the tibial components of sciatic nerves were isolated and the incision immediately closed. In group II, 1-cm segments of the nerve were removed and the silicon tubes filled with autogenous skeletal muscle were sutured in place. In group III, 1-cm segments of the nerve were removed and the silicon tubes filled without muscle were sutured in place. In group IV, 2-cm segments of the nerve were removed and the silicon tubes filled with autogenous skeletal muscle were sutured in place. In group V, 2-cm segments of the nerve were removed and the silicon tubes filled without muscle were sutured in place. At 16th week, the eletromyography, the light and transmission electron microscopy were performed. Nerve conduction study stimulating sciatic nerve proximal to the lesion and recording at gastrocnemius muscle showed that the compound muscle action potentials of the group II with 1 cm nerve defect filled with muscle were higher amplitudes than the group III without muscle. Compound muscle action potentials of the group IV with 2 cm defect filled with muscle showed similar results in comparison with the group V. The light and transmission electron microscpy showed that a good morphological pattern of nerve regeneration in 1 cm gap than 2 cm and in gap with muscle than gap without muscle.

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Beam and shadow effects occurring at connetions of tubes in the molecular flow (분자류에서 도관의 연결부에 나타나는 빔 효과와 그림자 효과)

  • 인상렬
    • Journal of the Korean Vacuum Society
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    • v.9 no.1
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    • pp.1-6
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    • 2000
  • An unexpected error is produced in calculating the transmission probability of a multipartite duct because of beam and shadow effects, if using a simple summation rule like the Oatley's equation. Particles moving in a tube are directed more or less towards the axis of the tube by the beam effect, and the length of a compound tube shortens virtually by the shadow effect originated from a reduction in the number of particles reaching the corner between two tubes of different cross-sections. Both effects make the transmission probability of the tube connected behind and consequently of the whole duct increase slightly. In this paper sources of the error in the calculation of the transmission probability are analyzed quantitatively and variations in the error depending on the dimensions of cylindrical tubes are calculated.

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Spring Back on the Compound Bending of the Plastic Fuel Tube for Automobile (자동차용 플라스틱 연료튜브의 복합 벤딩에 대한 스프링백)

  • Moon, C.Y.;Park, J.S.;Jeong, Y.D.
    • Journal of Power System Engineering
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    • v.7 no.2
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    • pp.51-55
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    • 2003
  • Recently the requirements for light weight and high performance of the automobile have increased. Especially, the plastic fuel tube makers have made their efforts to dove]op the various plastic fuel tube module with not only dimensional accuracy but also cost competitiveness. The experiment is performed to investigate spring backs for PA12 plastic fuel tubes in case of compound bending. In the experiment, steam bending process is adopted as bending method. In this study, the results we obtained are used to design the bending fixtures and the compound bending system.

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Measurement and Analysis of Bed Shear Stresses in Compound Open Channels using the Preston Tube (프레스톤튜브를 이용한 복단면 하도의 하상전단응력 측정 및 분석)

  • Lee, Du Han;Kim, Myounghwan;Kim, Won;Seo, Il Won
    • Ecology and Resilient Infrastructure
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    • v.4 no.4
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    • pp.207-215
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    • 2017
  • Hydraulic issues such as flow resistance, side wall correction, sediment, erosion and deposition, and channel design have close relation with distribution of bed shear stresses but the measurement of the distribution of bed shear stresses is not easy. In this study the Preston tube which makes possible relatively simple measurement of bed shear stresses is used to analyze the characteristics of bed shear distribution in compound open channels with different depth ratio. The Preston tubes are made and calibrated to develop the calibration formula and then they are applied to measure bed shear stress distribution in 5 cases depth ratio condition of compound channels. The results are compared with former experiment data, and characteristics of bed shear stress distributions are studied with different channel scales and Reynolds numbers. Although bed shear distributions with depth ratio show overall agreement with former studies, some differences are verified in bed shear variation, formation of inflection point in main channel, and distribution near floodplain junction which are due to high Reynolds number. Through the study applicability of the Preston tubes are also verified and characteristics of bed shear distribution in compound channels are suggested with Reynolds number and depth ratio.

A comparison of desorption efficiency by types of solvent for polar and non-polar organic compounds collected on activated charcoal tube (활성탄관에 포집된 극성 및 비극성 유기용제 분석시 탈착용매 종류에 따른 탈착효율 비교)

  • Son, Yonjoo;Kim, Hyunwook
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.7 no.1
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    • pp.3-18
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    • 1997
  • This study was conducted to evaluate desorption efficiencies by types of desorption solvent for polar and non-polar organic compounds collected on activated charcoal tubes. Analytes tested were toluene, m-xylene, isobutyl alcohol, n-butyl alcohol, cellosolve acetate, and butyl cellosolve. Three different concentration levels of spiked sample were made. Types of cosolvent mixed with the main solvent, $CS_2$, were methanol, pentanol, and dimethylformamide (DMF) and the cosolvent for methylenechloride was methanol. The amounts of cosolvent added to the main solvent were 1, 5, and 10% by volume (v/v%), respectively. The results were as follows: 1. For all mixed solvents except 1% methanol and 1% pentanol with $CS_2$, desorption efficiency significantly increased, compared with that of $CS_2$ alone. 2. Desorption efficiency increased by increasing analyte loading on charcoal tube regardless of mixed solvents used and the material polarity. 3. For all cosolvents mixed with $CS_2$ by 1% and 5% volume, desorption efficiency for non-polar compound was significantly higher than that of polar compound. For the 10% mixed solvents and the methylenechloride mixed with methanol, the results were opposite. 4. The lowest mean percent bias of 4.79% was obtained from the 5% DMF-$CS_2$ mixed solvent, followed by 4.82% from the 10% DMF-$CS_2$ solvent while the highest bias of 23.26% was from the solvent of $CS_2$ alone. Based on the results of this study, in order to increase desorption efficiency, it is recommended to add such cosolvents as methanol, pentanol, and DMF to $CS_2$, preferably 5% by volume for analyzing polar compounds collected in charcoal tubes.

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Relationship between NVOCs Concentration and Korean Red Pine (Pinus densiflora S. et Z.) Forest Environment in Spring Season (봄철 소나무숲의 NVOC 농도와 숲환경과의 상관관계)

  • Kim, GeonWoo;Kwon, ChiWon;Yeom, DongGeol;Joung, Dawou;Choi, Yoon Ho;Park, Bum-Jin
    • Journal of Korean Society of Forest Science
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    • v.103 no.3
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    • pp.483-489
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    • 2014
  • This study aimed at a scientific examination of the relationship between NVOCs concentration and the physical environment of red pine forest in spring season. Atmospheric NVOC samples in red pine forest was collected through five trials conducted from March to May 2013, using Tanax-Ta-charged disposable tubes and mini-pumps. At each trial, measurements were taken at three different points in daytime (sunrise, southing and sunset). For maximum accuracy, two tubes were used for each measurement at the same location, and the mean value was used for analysis. Compound analysis on the NVOC samples was done using the HS-SPME method and GC-MS. Analysis of the relationship between NVOC and the physical forest environment found higher concentrations of most substances, including ${\alpha}$-pinene and ${\beta}$-pinene, with higher temperature, dew point, and lower concentrations with higher wind velocity. The findings of this study offer scientific evidence which can inform the creation of 'healing forests' and 'recreational forests' as well as forest environment in general, helping to promote public health and recreational activities.