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1

Effect of Fe Content on the Contact Resistance of Electroplated Au-Fe Alloy Layers

Park H. S., Son I.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1503--1507

EN

In this study, variations in the contact resistance of electroplated Au-Fe alloy layers with Fe content were investigated. The contact resistance of electroplated Au-Fe alloy layers that were subject to thermal aging at 260°C in the atmosphere, tended to increase significantly with an increase in the Fe content. Through an analysis method employing X-ray photoelectron spectroscopy (XPS/ESCA) and Auger electron spectroscopy (AES), Ni oxides, such as NiO and Ni2O3, on the surface of the thermally aged electroplated Au-Fe alloy layers were observed. It is believed that the Ni oxide existing on the surface diffused from the underlying electroplated Ni layers to the surface through the grain boundaries in the electroplated Au-Fe layers during the thermal aging. As the Fe content in the electroplated Au-Fe layers increased, the grain size decreased. As the grain size decreases, more Ni oxide was detected on the surface. Therefore, with a rise in the Fe content, more Ni diffuses to the surface via grain boundaries, and more Ni oxide is formed on the surface of the electroplated Au-Fe layers, increasing the contact resistance of the electroplated Au-Fe alloy layers.

2

Sintering and Microstructures of SUS 316L Powder Produced by 3D Printing Process

Kim W. J., Nguyen H.-H., Kim H. Y., Nguyen M.-T., Park H. S., Kim J.-C.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1215--1218

EN

Selective laser sintering (SLS) is a type of laminating sintering technique, using CO2 laser with (metal, polymer, and ceramic) powders. In this result, the flake SUS 316L was used to achieve a high porous product, and compare to spherical type. After SLS, the porosity of flake-type sample with 34% was quite higher than that of the spherical-type one that had only 11%. The surface roughness of the flake SLS sample were also investigated in both inner and surface parts. The results show that the deviation of the roughness of the surface part is about 64.40μm, while that of the internal one was about 117.65μm, which presents the containing of high porosity in the uneven surfaces. With the process using spherical powder, the sample was quite dense, however, some initial particles still remained as a result of less energy received at the beneath of the processing layer.

3

Comparison Of Mercury Distribution Between The Types Of Spent Fluorescent Lamp

Rhee S. W., Park H. S., Choi H. H.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1297--1299

EN

Spent fluorescent lamps(SFLs) such as linear type lamp, compact type lamp and U-type lamp are used to estimate mercury distribution in the components of lamps. Determination of mercury concentration in the components of spent fluorescent lamp is performed by the DMA method. Mercury concentration in the components of spent fluorescent lamp can be varied with the manufactures of lamp. Mercury portion in phosphor powder and glass from any types of spent fluorescent lamp is estimated to be higher than 99% by the analysis of mercury distribution. Through mercury distribution in the components for SFLs, the mercury concentration in phosphor powder is much higher than that in other components regardless of the type of lamp. Hence, it is desirable that phosphor powder of spent fluorescent lamps should be controlled separately and safely.

4

Assignment of periods and priorities of messages and tasks in distributed control systems

Kim H.Y., Lee C.M., Jung M.S., Park H.S.

Systems Science

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2001

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Vol. 27, nr 2

61-72

EN

This paper presents a task and message-based scheduling method to guarantee the given end-to-end constraints including precedence constraints, time constraints, and period and priority of task and message. The method is the integrated one considering both tasks executed in each node and messages transmitted via the network and is designed to apply to the general distributed control system that has multiple loops and a single loop has sensor nodes with multiple sensors, actuator nodes with multiple actuators, controller nodes with multiple tasks, and several types of constraints. The assigning method of the optimal period and priority of task and message is proposed, using the presented task and message-based scheduling method.

5

From molecular precursors to new materials

Roesky H. W., Park H. S.

Bulletin of the Polish Academy of Sciences. Chemistry

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1998

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Vol. 46, No. 3

285-288

EN

Preparation of gallium nitride is described using the single source precursor (Et2GaNH2)3. The thin films of GaN formed were characterized using various physical methods such as Auger spectroscopy, X-ray diffraction and AFM image of the surface, respectively.