• 융합정보논문지
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• 제9권12호
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• pp.147-156
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• 2019

동심 이중관에서 기본유체 물과 나노입자 산화알미늄의 혼합인 나노유체를 적용한 대향유동을 유한체적법의 수치적 방법으로 열전달 특성을 규명하였다. 고온유체는 내부 원형관으로 흐르며 열을 외부 환형관으로 흐르는 저온유체로 전달한다. 고온유체와 저온유체의 체적유량 및 나노입자의 체적농도를 변수로 두어 열전달 및 유동 특성을 조사했다. 결과는 나노입자의 체적농도와 체적유량의 증가함에 따라 열전달 성능이 증가함을 보였다. 외부와 내부 관 모두에서 나노유체인 경우가 기본유체보다 나노입자의 체적농도가 8%일 때 나노유체가 열전달 성능이 최대 17% 증가하는 것을 확인했다. 또한 기본유체에 비해 환형관의 대류열전달 계수는 최대 31% 증가함을 보였으며 열교환기의 유용도는 약 20%가 상승함을 확인하였다. 하지만 나노입자의 체적농도가 8%일때 마찰인자가 최대 136% 커지는 것을 확인하였다.

• Structural Engineering and Mechanics
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• 제58권5호
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• pp.931-947
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• 2016

The effects of nanotechnology and smartness on the buckling reduction of pipes are the main contributions of present work. For this ends, the pipe is simulated with classical piezoelectric polymeric cylindrical shell reinforced by armchair double walled boron nitride nanotubes (DWBNNTs), The structure is subjected to combined electro-thermo-mechanical loads. The surrounding elastic foundation is modeled with a novel model namely as orthotropic nonhomogeneous Pasternak medium. Using representative volume element (RVE) based on micromechanical modeling, mechanical, electrical and thermal characteristics of the equivalent composite are determined. Employing nonlinear strains-displacements and stress-strain relations as well as the charge equation for coupling of electrical and mechanical fields, the governing equations are derived based on Hamilton's principal. Based on differential quadrature method (DQM), the buckling load of pipe is calculated. The influences of electrical and thermal loads, geometrical parameters of shell, elastic foundation, orientation angle and volume percent of DWBNNTs in polymer are investigated on the buckling of pipe. Results showed that the generated ${\Phi}$ improved sensor and actuator applications in several process industries, because it increases the stability of structure. Furthermore, using nanotechnology in reinforcing the pipe, the buckling load of structure increases.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.754-758
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• 2001

A new kind of piezoelectric actuation structure named double amplified multilayer actuator is proposed. Double amplified multilayer actuator combines both dimentional and flextensional amplification concepts. As a result the displacement of the actuator can be more than one hundred times larger than the displacement of multilayer actuator and can be used in in-pipe locomation robot such as an endoscope actuator. This paper studied the dependence of displacement on actuator parameters theoretically and experimentally.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 Proceedings of The 6th korea-china joint workshop on nuclear waste management
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• pp.269-279
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• 2005

In this study, detectors characteristics for simultaneous counting of alpha and beta ray in a pipe were estimated. The detector were composed of thin ZnS(Ag) scintillator and plastic detector. The scintillator for counting alpha particles has been applied a polymer composite sheet, having a double layer structure of an inorganic scintillator ZnS(Ag) layer adhered onto a polymer sub-layer. The other for counting beta particles used a commercially available plastic scintillator. It was confirmed that the detectors were suitable for counting the in-pipe contamination.

• 동력기계공학회지
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• 제20권5호
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• pp.72-77
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• 2016

The present study investigates noise and condensation characteristics of polyvinyl chloride (PVC), which is widely used for drainage piping materials, complex double structure by comparing to those of PVC single structure piping materials. In addition, effects of insulation on drainage noise has been measured experimentally. As the results of the experiments, noise reduction effect of PVC complex double structure is superior to that of PVC single structure in terms of elbow and vertical piping materials which are employed for drainage pipes of toilet bowls and bathtub. The insulation barely have effect on the noise reduction in case of the PVC single structure since there is almost no changes in noise occurrence even though the insulation is applied on both elbow and vertical piping materials. Temperature differences between inside and outside of the pipes have been measures for the PVC single and complex double structures as well. In consequence, outside temperature of the PVC complex double structure is higher than that of the PVC single structure. The condensation occurrence time of the PVC complex double structure shows a distinct difference from that of the PVC single structure, thus, the PVC complex double structure has outstanding effect on preventing the condensation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.817-818
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• 2012

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2004년도 추계 학술발표회 논문집
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• pp.31-36
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• 2004

• 한국소음진동공학회논문집
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• 제12권5호
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• pp.374-379
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• 2002

A new active muffler system has been developed and its superior performance on both noise reduction and engine torque increase is demonstrated with experiment. Main characteristic of the proposed muffler system is the use of destructive interference by transmission path difference of divided exhaust pipes to reduce major exhaust noise components thereby overcoming problems of other active exhaust noise control methods. The exhaust pipe is divided into two sections and joined again downstream. One divided pipe has a sliding mechanism to vary its length, which is controlled to make half wavelength transmission path difference for the major engine rpm frequency. In this system one divided pipe is used to control major rpm frequency and its Harmonics and another pipe is used to control noise component double the frequency of rpm. An after-market tuning muffler, which has very simple internal structure and minimal back pressure, is also installed to remove remaining wideband noise. To make the system to be small enough to be practical, conventional muffler is also installed and used in low rpm range and active muffler is only employed in high rpm range. Noise reduction of the proposed system is comparable to conventional passive muffler. The engine dynamo test has proved the proposed system can recover almost all the torque lost by conventional muffler.

• Computers and Concrete
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• 제20권4호
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• pp.483-490
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• 2017

This paper studies on the behavior of reinforced concrete (RC) pipes used in basic sanitation in the conduction of storm water and sanitary sewer. Pipes with 800 mm and 1200 mm in diameter were analyzed. The 800 mm pipes were built with simple reinforcement and the 1200 mm pipes with double reinforcement. For the two diameters of pipes the presence or absence of the pocket was evaluated, and the denomination of each one is spigot and pocket pipe (SPP) and ogee joint pipe (OJP), respectively. The 3D numerical models reproduce the three-edge-bearing test that provides information about the strength and stiffness of the reinforced concrete pipes. The validation of the computational models was carried out comparing the vertical and horizontal displacements on the springline and crown/invert and it was also evaluated the reinforcement strains and the crack pattern. As a main conclusion, the numerical models represented satisfactorily the behavior of the pipes and can be used in future studies in parametric analysis.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.333-338
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• 2006

This study is a research on Dual Bore heat pipe to investigate the ability of heat transport ability, heat resistance and difference of heat transport ability according to the type of heat pipes. As the result of this research, we got several conclusions. Each pipe of Dual Bore in one section has a similar heat transfer capability. In the range between $-20^{\circ}C$ and $60^{\circ}C$ the heat transfer capability is double than single bore which was analyzed by menas of GAP program. Heat resistance is below $0.05^{\circ}C$/W at every point, and it tells aluminum-ammonia heat pipes are proper for satellite.