• International Journal of Automotive Technology
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• 제6권5호
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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.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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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.

• 대한기계학회논문집A
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• 제28권11호
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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.

• 한국산업융합학회 논문집
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• 제4권4호
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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%.

• Archives of Reconstructive Microsurgery
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• 제12권1호
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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.

• 한국진공학회지
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• 제9권1호
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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.

• 동력기계공학회지
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• 제7권2호
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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.

• Ecology and Resilient Infrastructure
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• 제4권4호
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• pp.207-215
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• 2017

하도의 흐름 저항, 측벽 보정, 유사량, 하도 침식과 퇴적, 하도 설계 등의 수리학적 문제는 하상전단응력의 분포와 밀접한 관계가 있으나 하상전단응력 분포를 측정하는 것은 쉽지 않다. 본 연구에서는 간편하게 하상전단응력을 측정할 수 있는 프레스톤튜브를 이용하여 복단면의 하도의 하상전단응력 분포를 측정하고 수심비에 따른 전단응력분포 특성을 고찰하였다. 이를 위해 프레스톤튜브를 제작하여 검정실험을 통해 검정식을 개발하였다. 실험은 5가지 수심비 조건에 대해서 수행하여 전단응력분포를 측정하였다. 복단면 하도의 전단응력분포 특성은 기존 실험연구와 대체로 일치하였으며, 레이놀즈수 증가로 발생하는 전단응력의 변동성, 주수로 전단응력의 변곡점 형성, 홍수터 접합부 부근 전단응력 분포 특성 등에서 차이점을 확인하였다. 본 연구를 통해 프레스톤튜브를 이용한 하상전단응력측정 적용성을 확인하였으며 레이놀즈수와 수심비에 따른 복단면 하도의 전단응력분포 특성을 제시하였다.

• 한국산업보건학회지
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• 제7권1호
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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.

• 한국산림과학회지
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• 제103권3호
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• pp.483-489
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• 2014

본 연구는 봄철 소나무숲의 NVOC 농도와 숲의 물리환경과의 상관관계에 대하여 과학적으로 밝히기 위한 목적으로 수행되었다. 소나무숲의 대기중 NVOC의 포집을 위해 2013년 3월부터 2013년 5월까지 총 5회의 실험을 진행하였으며 Tanax-Ta가 충진된 1회용 튜브와 미니펌프를 사용하여 포집하였다. 매회의 실험마다 일중시간동안 총 세 번의 시간(일출, 남중, 일몰)에 측정을 하였으며 오차를 줄이기 위하여 같은 지점에서 두 개의 튜브를 사용하여 측정 후 분석한 평균값을 사용 하였다. 포집된 NVOC 물질 분석은 HS-SPME법을 사용하여 GC-MS로 분석하였다. 봄철 소나무숲의 NVOC 농도와 숲의 물리환경과의 상관관계에 대하여 분석한 결과, ${\alpha}$-pinene, ${\beta}$-pinene 등 대부분의 물질에서 온도, 이슬점이 높아질수록 농도가 높아졌으며 풍속이 클수록 농도가 낮아졌다. 본 연구에서 얻어진 자료들은 치유의 숲, 자연휴양림 조성 및 숲 환경에 대한 과학적인 근거를 제시함으로써 국민들의 건강증진과 여가활동에 유익한 정보로 사용 될 것이라 기대된다.