• 한국주조공학회지
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• 제27권2호
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• pp.83-87
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• 2007

Aluminum plates of the same materials as the foam were attached by the casting process inserting the foam as a core to investigate the tensile property of open cell foams. Tensile properties of the open cell 6063 aluminum alloy foam of $10{\sim}30$ PPI were measured before and after heat treatment. Densities of test specimens were between 0.14 and $0.29g/cm^3$. Tensile strength of the 6063 aluminum foam after heat treatment showed little change. C values were in the range of $0.41{\sim}0.87$ for as cast foams and $0.11{\sim}0.27$ for T6 heat treated foams in the eq. of ${\sigma}^* _{pl}/{\sigma}_{ys}=C({\rho}/{\rho}_s)^{1.5}$, and increased with increase in the cell size.

• 전기의세계
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• 제19권4호
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• pp.18-23
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• 1970

A neutron detector, in general, can not be utilized as the thermal neutron detecting chamber in the nuclear power reactor, especially P.W.R. due to the characteristics of high temperature, high pressure and high neutron flux in a reactor vessel. We have performed an experiment to detect the thermal neutrons at 400.deg. C and high flux of thermal neutron in a power reactor. Coating boron-10 on the aluminium plates by means of surface diffusion method at 600.deg. C for 5 hours in an electric furace, also we made a typical chamber which was compensated ionization chamber filled with free air as an ionization gas. It was checked the chamber characteristics in the TRIGA MARK-II Reactor at the power level from zero to 250KW. The chamber current showed a perfect linear increase to power increase. However, many variation of the measured current were observed within the power of 50KW.

• Journal of Welding and Joining
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• 제27권3호
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• pp.44-51
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• 2009

In this study, welding distortion analysis is performed for various design of tube shape structures which are assembled with aluminum sheet metal. Aluminum 5052 plates of 1mm thickness are used to analyze. An efficient keyhole model, as a welding heat source, is used for the prediction of full penetration weld size and shape which is required for the thermal analysis. The thermal and mechanical material properties are considered as temperature dependent functions, due to the high temperature variations during the welding. The numerical model is calculated by using a commercial software and evaluated with the experiments. The calculation results could make a comparative study in the view of distortion for the various size and shape of structure.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.549-550
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• 2006

Mobile fuel cell is highlighted in these days because mobile fuel cell can contain more energy than existing batteries. Nowadays mobile devices like cellular phone, PMP(portable multi-media player), notebook, and etc. need more energy, But existing batteries like Li-ion or Ni-MH batteries are not going to satisfy such demands. In this paper, mobile fuel cell is developed. Its size is 50*70*8mm and it is made of aluminium plates. The fuel cell type is PEM and the fuel is pure hydrogen and oxygen.

• 한국항해항만학회지
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• 제31권10호
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• pp.825-831
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• 2007

일반적으로 선박 및 해양구조물에서 사용하고 있는 고강도 알루미늄 재료들은 일반 강재에 비해서 많은 이점들을 가지고 있다. 이러한 알루미늄 재료들은 여러 분야에 걸쳐서 폭넓게 사용되고 있으며, 특히, 초고속 선박의 선체와 갑판부에 많이 이용되어지고 있고, 교량구조물에 사용되는 박스 거더, 그리고 해양구조물의 갑판부와 선측구조에도 널리 이용되고 있다. 이러한 알루미늄 구조는 전체적인 구조부재의 중량을 감소하게 하면서 선속의 증가를 가져온다. 일반적인 강구조물의 응력-변형률 관계와 비교하여 보면, 용접가공에 의하여 발생되는 열영향부의 존재로 인하여 상당히 다르게 나타난다. 왜냐하면, 강구조물에 비해 열전도율이 높아서, 열영향부(heat affected zone, HAZ)의 영향이 크게 작용하기 때문이다. 본 논문에서는 종방향 압축하중을 받는 알루미늄 보강 판넬의 최종강도 특성에 대하여, 열영향부의 범위를 변화한 유한요소해석을 통하여, 열영향부의 범위와 파굴 및 최종강도 거동의 관계에 대해서 고찰하였다.

• 한국표면공학회지
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• 제50권3호
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• pp.198-205
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• 2017

Thermal dissipation was investigated for poly methyl methacrylate (PMMA) composite films containing graphite and multi wall carbon nanotube(CNT) powders as filler materials. After mixing PMMA with fillers, solvent, and dispersant, the pastes were prepared by passing through a three roll mill for three times. The prepared pastes were coated $15{\sim}40{\mu}m$ thick on a side of 0.4 mm thick aluminium alloy plate and dried for 30 min at $150^{\circ}C$ in an oven. The content of fillers in dried films was varied as 1, 2, and 5 weight % maintaining the ratio of graphite and CNT as 1:1. Raman spectra from three different samples exhibited D, G and 2D peaks, as commonly observed in graphite and multi wall CNT. Among those peaks, D peak was prominent, which manifested the presence of defects in carbon materials. Thermal emissivity values of three samples were measured as 0.916, 0.934, and 0.930 with increasing filler content, which were the highest ever reported for the similar composite films. The thermal conductivities of three films were measured as 0.461, 0.523, and $0.852W/m{\cdot}K$, respectively. After placing bare Al plate and film coated samples over an opening of a polystyrene box maintained for 1 h at $92^{\circ}C$, the temperatures inside and outside of the box were measured. Outside temperatures were lower by $5.4^{\circ}C$ in the case of film coated plates than the bare one, and inside temperatures of the former were lower by $3.6^{\circ}C$ than the latter. It can be interpreted that the PMMA composite film coated Al plates dissipate heat quicker than the bare Al plate.

• 한국정밀공학회지
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• 제15권8호
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• pp.17-25
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• 1998

Aluminum alloys have low density, relatively high strength and yield strength, good plasticity, good machinability, and high corrosion and acid resistance. Therefore, they are suitable for large containers for the food, chemical and other industries. Large containers are often bodies of revolution consisting of shell courses, stiffening rings, heads and other elements joined by annular welds. Larger containers have longer welds and require greater leak-tightness and higher weld mechanical properties. The LNG tank consists of aluminum plates with various sizes, so its construction should by divided by several sections. Moreover, each section has its own sub-section consisted of several aluminum plates. To guarantee the quality of huge LNG tank, therefore, the precise control of plate dimension should by urgently needed in conjunction with the appropriate selection of process parameters such as cutting speed, depth of cut, rotational speed and so on. In this paper, a manufacturing system was developed to implement automatic circular tracking in height direction and automatic circular interpolation in depth of cut direction. Also, the neural network based on the backpropagation algorithm was used to predict the cutting quality and motor load related with the life time of the developed system. It was revealed that the manufacturing system and the neural network could be effectively applied to the bevelling process and to predict the quality of machined area and the motor load.

• 열처리공학회지
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• 제25권1호
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• pp.1-5
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• 2012

The purpose of this study is to prepare a high strength fiberglass reinforced metal. Aluminum covering was carried out over carbon materials such as carbon fiber in order to increase their wettability to molten metals such as aluminum. A sputtering apparatus with a cylindrical target was fabricated to carry out the covering. Sputtering was caused by glow discharge between the target and the two anode plates attached to its top and bottom. As the substrate for preliminary test, a thin carbon wire was used instead of carbon fiber, and the wire was placed at the central axis of the target. Aluminium coating was formed on the whole surface of the substrate. The formation rate and structure of coating were varied by controlling the electrical potential of substrate. When the substrate was electrically isolated, coating with columnar structure was formed with a formation rate of $15{\mu}m/hr$. In case of grounded substrate, coating with amorphous structure was formed with a formation rate of $7{\mu}m/hr$.

• Structural Engineering and Mechanics
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• 제31권4호
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• pp.439-451
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• 2009

The paper deals with the problem related to the modelling of riveted assemblies for crashworthiness analysis of full-scale complete aircraft structures. Comparisons between experiments and standard FE computations on high-energy accidental situations onto aluminium riveted panels show that macroscopic plastic strains are not sufficiently localised in the FE shells connected to rivet elements. The main reason is related to the structural embrittlement caused by holes, which are currently not modelled. Consequently, standard displacement FE models do not succeed in initialising and propagating the rupture in sheet metal plates and along rivet rows as observed in the experiments. However, the literature survey show that it is possible to formulate super-elements featuring defects that both give accurate singular strain fields and are compatible with standard displacement finite elements. These super-elements can be related to the displacement model of the hybrid-Trefftz principle of the finite element method, which is a kind of domain decomposition method. A feature of hybrid-Trefftz finite elements is that they are mainly used for elastic computations. It is thus proposed to investigate the possibility of formulating a hybrid displacement finite element, including the effects of a hole, dedicated to crashworthiness analysis of full-scale aeronautic structures.

• 대한전자공학회논문지
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• 제24권1호
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• pp.102-109
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• 1987

This study is carrier out to investigate the carrier injection and the characteristics of trapping for the CVD deposited Al2O3 film on Si substrates. Samples used are metal -Al2O3-Si Structure in which metal field plates are used with Aluminium or God. Canier injection and trapping, which result in flat band voltalge shift, occur at fields as low as 1~2 MV/cm. An approximate method is proposed for computing the location of the centroid of the trapped electrons in this paper. Results show that carriers are trapped near the injecting interface at fields less than about 5MV/cm. Because of continued charging, a steady state can not be reached. Therefore the unique I-V curve is obtained when the traps are initially empty. By utilization of applied voltage on each point of the fresh device sample, it is measured the I-V surves for two polarities of applied voltage. The current densities observed in the Al2O3 films are much larger than those obtained in SiO2.