• Transactions on Electrical and Electronic Materials
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• v.15 no.3
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• pp.155-158
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• 2014

The phase transformation of Sn-Pb-Bi solder for photovoltaic ribbon during soldering was studied using real-time synchrotron x-ray scattering. At room temperature, Sn and Pb crystal phases in the solder existed separately. By heating to $92^{\circ}C$, a new PbBi alloy crystal phase was formed, which grew further up to $160^{\circ}C$. The Sn crystal phase first started to melt at $160^{\circ}C$, and was mostly melted at $165^{\circ}C$. In contrast, the Pb and PbBi crystal phases started to melt at $165^{\circ}C$, and were mostly melted at $170^{\circ}C$. The useful result was obtained, that the solder's melting temperature decreased from $183^{\circ}C$ to $170^{\circ}C$ by addition of a small amount of Bi atoms to the eutectic Sn62-Pb38 (wt%) solder. Our study first revealed the detailed in-situ phase transformation of Sn-Pb-Bi solder during heating to the eutectic temperature. Considering the results of peel strength and hardness, adding 1 wt% of Bi atoms to the Sn62-Pb38 (wt%) solder produced an appropriate composition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.27-30
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• 2006

In this paper, the undoped and Co-doped $Zn_4SnSe_6$ single crystals grown by the chemical transporting reaction(CTR) method using iodine as a transporting agent are investigated. For the crystal growth, the temperature gradient of the CTR furnace was kept at $680^{\circ}C$ for the source zone and at $780^{\circ}C$ for the growth zone for 7days. It was found from the analysis of x-ray diffraction that the $Zn_4SnSe_6$ and $Zn_4SnSe_6Co^{2+}$ compounds have a monoclinic structure. The direct optical energy band gap of the $Zn_4SnSe_6$ and $Zn_4SnSe_6Co^{2+}$ single crystals at 300K were found to be 2.146eV and 2.042eV.

• Journal of Powder Materials
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• v.25 no.6
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• pp.507-513
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• 2018

This study investigates the viability of using a Na-ion battery with a tin(Sn) anode to mitigate the vulnerability caused by volume changes during discharge and charge cycling. In general, the volume changes of carbon material do not cause any instability during intercalation into its layer structure. Sn has a high theoretical capacity of $847mAh\;g^{-1}$. However, it expands dramatically in the discharge process by alloying Na-Sn, placing the electrode under massive internal stress, and particularly straining the binder over the elastic limit. The repeating strain results in loss of active material and its electric contact, as well as capacity decrease. This paper expands the scope of fabrication of Na-ion batteries with Sn by fabricating the binder as an auxetic structure with a unique feature: a negative Poisson ratio (NPR), which increases the resistance to internal stress in the Na-Sn alloying/de-alloying processes. Electrochemical tests and micrograph images of auxetic and common binders are used to compare dimensional and structural differences. Results show that the capacity of an auxetic-structured Sn electrode is much larger than that of a Sn electrode with a common-structured binder. Furthermore, using an auxetic structured Sn electrode, stability in discharge and charge cycling is obtained.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.93-98
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• 2005

Rewritable optical disk is one of the essential data storage media in these days, which takes advantage of the different optical properties in the amorphous and crystalline states of phase change materials. As well known, data transfer rate is one of the most important parameter of the phase change optical disks, which is mostly limited by the crystallization speed of recording media. Therefore, we doped Sn/Bi to $Ge_2Sb_2Te_5$ alloy in order to improve the crystallization speed and investigated the dependence of phase change characteristics on Sn/Bi doping concentration. The Sn/Bi doped $Ge_2Sb_2Te_5$ thin film was deposited by RF magnetron co-sputtering system and phase change characteristics were investigated by X-ray diffraction (XRD), static tester, UV-visible spectrophotometer, electron probe microanalysis (EPMA), inductively coupled plasma mass spectrometer (ICP-MS) and atomic force microscopy (AFM). Optimum doping concentration of Bi and Sn were 5${\~}$6 at.$\%$ and the minimum time for crystallization was below than 20 ns. This improvement is correlated with the simple crystalline structure of Sn/Bi doped $Ge_2Sb_2Te_5$ and the reduced activation barrier arising from Sn/Bi doping. The results indicate that Sn/Bi might play an important role in the transformation kinetics of phase change materials..

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.334-338
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• 1994

This report details the microscopic aspects of grain boundary cracking in Pb-Sn eutecticduring displacement-controlled mechanical tests performed over a range of low frequency ($10^{-3}-10^{-5}$/s)and moderate strain range (0.2 - 1 %) where is the most technologically relevant to solder jointssubjected to thermal cycling. It is shown that intergranular cracking begins with the appearance ofcrack-like features (CLF's), which can be seen due in part because they are associated with grainboundary sliding, and is able to be described by certain stages of isolated crack growth. In the initialstages CLF's are not ture cracks but instead what I shall call "proto-cracks" where grain boundarysliding begins to damage the gram boundary at the surface. At some point during the initiation stagesonce proto-cracks become ture cracks, they develop into isolated cracks and the growth of isolatedcracks is eventually accomplished by coalescence, resulting in 5 stages of cracking.ing in 5 stages of cracking.

• Journal of Digital Contents Society
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• v.15 no.5
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• pp.621-630
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• 2014

The purpose of this study is to extract metaphor characteristics of Social Network Service. Social Network Service is different from existing media only available in one-way communication, each individual expands opinion by sharing daily life and opinion directly and interpreting another user's post. This Study premise that the reason of converting from passive reader to active enunciator is the metaphor characteristics of Social Network Service by 'Source Domain' and 'Target Domain'. In addition, this study examines the meaning of structure user's text production and interpreting based triple mimesis of Paul Ricoeur. This study has significance as arguing with existing study on SNS as metonymic media and suggesting metaphor characteristics and meaning of Social Network Service.

• Journal of Korea Multimedia Society
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• v.17 no.2
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• pp.180-190
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• 2014

Social network services are increasingly being used in organizational settings to improve relationships among employees and enhance prospects for information exchange and cooperative work. Social Networking Service(SNS) has deeply penetrated organizational job settings, influencing multiple aspects of employee's life. This study is designed to explore the impact of SNS engagement on the job performance mediated as team cooperation and decision making quality effects. Data were collected from 146 employees who use organizational SNS in there company. Factor analysis and structural equation method are employed. Results from a survey accompanied by the substantial impacts of organizational employee's social networking engagement on social learning processes and outcomes. SNS engagement not only directly influences organizational employee's job performance, but also helps their team cooperation and decision making quality from others and adapt to organizational culture, both of which play prominent roles in improving their job performance.

• Journal of information and communication convergence engineering
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• v.7 no.1
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• pp.72-77
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• 2009

Three different procedures for adding Pd compounds to $SnO_2$ particles have been investigated. These processes are: (1) coprecipitation; (2) dried powder impregnation; and (3) calcined powder impregnation. The microstructures of $SnO_2$ particles have been analyzed by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). In the coprecipitaion method, the process does not restrain the growth of $SnO_2$ particles and it forms huge agglomerates. In the dried powder impregnation method, the process restrains the growth of $SnO_2$ particles and the surfaces of the agglomerates have many minute pores. In the calcined powder impregnation method, the process restrains the growth of $SnO_2$ particles further and the agglomerates have a lot more minute pores. The sensitivity ($S=R_{air}/R_{gas}$) of the $SnO_2$ gas sensor made by the calcined powder impregnation process shows the highest value (S = 21.5 at 5350 ppm of $C_3H_8$) and the sensor also indicates the lowest operating temperature of around $410^{\circ}C$. It is believed that the best result is caused by the plenty of minute pores at the surface of the microstructure and by the catalyst Pd that is dispersed at the surface rather than the inside of the agglomerate. Schematic models of Pd distribution in and on the three different $SnO_2$ particles are presented.

• Current Photovoltaic Research
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• v.1 no.2
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• pp.109-114
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• 2013

$Cu_2ZnSnS_4$ (CZTS) nanoparticles were synthesized by a solvothermal method using copper (II) acetate, zinc acetate, tin chloride, and sulfur in diethylenetriamine solvent. Binary sulfide particles such as CuS, ZnS, SnS, and $SnS_2$ were obtained at $180^{\circ}C$; single-phase CZTS nanoparticles were obtained at $280^{\circ}C$. CZTS nanoparticles with spherical shape and grain size of 40 to 60 nm were obtained at $280^{\circ}C$. In the middle of 180 and $280^{\circ}C$, CZTS and ZnS phases were found. The time variation of reaction at $280^{\circ}C$ revealed that an amorphous state formed first instead of binary phases and then the amorphous phase was converted to crystalline CZTS state; it is different reaction path way from conventional solid-state reaction path of which binary phases react to form CZTS. CZTS films deposited and annealed from single-phase nanoparticles showed porous microstructure and poor adhesion. This indicates that a combination of CZTS and other flux phase is necessary to have a dense film for device fabrication.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.770-775
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• 2002

We present the band lineups of G $e_{1-}$x S $n_{x}$ G $e_{1-}$y S $n_{y(001)}$ heterostructures for the new devices. The energy gap of the bulk G $e_{1-}$x S $n_{x}$ alloy is calculated by taking into account the Vegard's law. The change of the energy gap due to the strain is understood in terms of the deformation Potential theory The valence band offset is obtained from the average bond energy model, where the changes of the band offset due to alloy compositions and strain are included. It is found that Ge/G $e_{1-}$y S $n_{y(001)}$ heterostructure has a staggered lineup type for 0$\leq$0.06 and a straddling one for 0.06$\leq$0.26. Meanwhile, Ge/G $e_{l-y}$ S $n_{y(001)}$ heterostructure has a staggered lineup type for 0$\leq$0.19 and a broken-gap one for 0.19$\leq$0.26. As a result, the various type of the G $e_{1-}$x S $n_{x}$ G $e_{1-}$y S $n_{y(001)}$ heterostructure can be applied for the useful device.evice.