• 비파괴검사학회지
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• 제21권5호
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• pp.526-531
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• 2001

공통축 형태로 배치된 비자성체 이중관에 있어서 유한요소해석 상용 소프트웨어와 실험적인 방법을 각각 이용하여 원격장 와전류 에너지의 전달 경로를 연구하였다. 연구결과 이중관에 있어서 원격장 와전류 에너지는 두 관 사이의 공간을 따라 흐르는 것이 아니라, 단일 튜브의 경우와 마찬가지로 외측 튜브의 외면을 따라 흐름을 확인하였다. 이는 원격장 와전류 효과의 관벽투과 특성이 이중관에 있어서도 유효함을 보여주는 것이다. 따라서, 중수로형 핵연료 채널과 같은 이중관 형태를 대상으로 내관 및 외관의 내 외부 결함 탐상, gap 분포 및 지지대의 위치 확인 등에 원격장 와전류 방법의 관벽투과 특성이 응용될 수 있음을 보였다.

• 한국연소학회지
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• 제18권2호
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• pp.1-7
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• 2013

Flame stabilization characteristics of premixed flames in narrow annular coaxial tubes (NACT) were investigated experimentally. The NACT burner was proposed as a model of a cylindrical refractory burner, and it was made of quartz tubes. Flame stabilization conditions affected by the characteristic length of the burner was investigated with the variation of the equivalence ratio and the flow rates. Flame behaviors in narrow spaces could be directly observed. Conclusively, more wide flame stabilization conditions could be obtained at the case of the decreased channel scale. A flame instability, such as combustion noise was detected concerned with the flame oscillation observed at the surface of multi channel stage. Some flame propagation characteristics had complicated tendencies that may exist in practical porous-media combustors. Therefore, this NACT burner can be a basic configuration for the development of flame stabilization model in porous media combustor, and it will enhance our understanding about the behavior of flames in meso-scale combustion spaces.

• 한국연소학회지
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• 제18권3호
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• pp.24-30
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• 2013

Flame stabilization characteristics of premixed flames in an annular coaxial 5-tubes burner (AC5TB) were investigated experimentally. The AC5TB was made of five quartz tubes, and the flame stabilization conditions in that burner were investigated with the variation of equivalence ratio and the flow velocities. Flame behaviors inside of narrow annular tubes could be observed directly. Overall flame stabilization conditions were similar to that of the previous study, while the flame behaviors and structures were different mainly due to the controlled uniform distribution of the velocities in channels. Flame flashback conditions were thought to be governed by the competition between heat release rate, heat loss and heat recirculation in each channel. Stationary flames at a fixed location were compared in its velocity distribution and burned gas temperature across the channel. This AC5TB can be a basic configuration for the development of flame stabilization model of porous media combustors, and it will help understand about the real behavior of flames in meso-scale combustion spaces.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1990년도 봄 학술발표회 논문집
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• pp.44-49
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• 1990

This study is a seismic analysia of absorber rod in KMRR Reactivity Control Mechanism. The model being studied i8 two coaxial tubes (control absorber rod and flow tube) immersed in the water and partially coupled (overlap) by water Hap. The hydrodynamic mass effects by the water in each surrounding conditions are considered in the model. The natural frequencies, stresses and displacements of the system due to Safe Shutdown Earthquake are computed in the cases of in-phase modes and out-of-phase modes of two coaxial tubes. The results show that maximum stresses are well below the allowable limit and maximum displacements at the ends of both tubes in out-of-phase modes are so huck that the tubes contact each other in the overlap zone.

• 한국태양에너지학회 논문집
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• 제24권3호
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• pp.27-38
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• 2004

A numerical investigation has been carried out for a solar system, which consists of all glass solar vacuum tubes Water is heated as it flows through the coaxial fluid conduit inserted in each tube. The space between the exterior of the fluid conduit and the glass tube is filled with antifreeze solution. This is to facilitate heat transfer from the solar heated absorber surface to water and to prevent the functional problems due to freezing in frigid weather conditions. A one-dimensional steady state model is fully described which will be used to develop three-dimensional model using STAR-CD. These models could be used efficiently in designing all-glass solar collector tubes with different geometrical parameters other than those considered in the present analysis. Results show good agreement when compared with other experimental data demonstrating the reliability of the present model.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.567-570
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• 2006

A numerical study has been carried out for a solar water heater which consists of double skin solar vacuum tubes. Water is heated as it flows through the coaxial fluid conduit inserted in each tube. The space between the exterior of the fluid conduit and the glass tube is tilled with antifreeze solution. This is to facilitate heat transfer from the solar heated absorber surface to water and to prevent the functional problems due to freezing in frigid weather conditions. A one-dimensional steady state model is fully described which will be used to develop three-dimensional model using STAR-CD. These models could be used efficiently in designing double skin solar collector tubes with different geometrical parameters other than those considered in the present analysis. Results show a good agreement when compared with other experimental data demonstrating the reliability of the one-dimensional model employed.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.357.2-357
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• 2001

• 전산구조공학
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• 제3권3호
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• pp.141-146
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• 1990

본 연구에서는 다목적연구로 반응도제어장치의 제어봉에 대한 내진해석을 수행하였다. 해석모델은 물속에 잠겨있는 두개의 관(중성자흡수봉 및 유동관)이 동심축상에 있으며 부분적으로 중첩된 두 관끝단의 유체틈에 의해 서로 동적으로 연결되어 있다. 유체에 의한 동적질량을 고려한 고유진동수를 구하고 안전정지지진에 의해 발생하는 최대응력과 최대변위를 동위상 및 역위상 거동별로 각각 구하였다. 해석결과 최대응력은 허용치보다 작게 나타나 구조적인 건전성은 입증되었으나, 최대변위는 두 개의 관이 서로 부딪히고 중성자흡수봉은 주위의 다른 벽에도 부딪히는 현상을 수발함을 알 수 있었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권12호
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• pp.791-797
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• 1999

Recently the ozone generation system is well used for cleaning the contaminated water by using the strong oxidization effects of ozone. In this paper the concentration, yield and generation quantity of the ozone by the Surface-Silent Discharge According to the Length of Coaxial Electrode is described. The electrodes composed of 3 electrodes-2 gaps are coaxial type and the ozone generation tube were designed and fabricated from the point of view of the energy efficiency, stability and easy control. To investigate the ozone generation dependency on electrode length, a few discharge tubes with different lengths were fabricated. The experimental equipments were provided with cooling system and dehumidifier for the many testing conditions. The main results show that the concentration, yield and generation quantity of ozone are improved by decreasing gas temperatures and increasing electrode lengths.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.249-258
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• 2004

We investigated structural phases of potassium intercalated into carbon nanotubes using a structural optimization process applied to atomistic simulation methods. As the radius of carbon nanotubes increased, structures were found in various phases from an atomistic strand to multishell packs composed of coaxial cylindrical shells and in helical, layed, and crystalline structures. Numbers of helical atom rows composed of coaxial tubes and orthogonal vectors of a circular rolling of a triangular network could explain multishell phases of potassium in carbon nanotubes.