• Journal of the Microelectronics and Packaging Society
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• v.17 no.2
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• pp.11-20
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• 2010

The effects of heat treatment on matte pure tin-plated Cu leadframes at high temperature and humidity conditions were investigated. After 1800 hrs of storage at $55^{\circ}C/85%$ RH, approximately 14.5 ${\mu}m$ long striation-shaped whiskers were observed on the surface of the without postbake treatment (WOPB) samples, while no whiskers were found in with postbake treatment (WPB) samples. The preferred orientations of Sn grains in WOPB and WPB sample did not change after the postbake treatment at $125^{\circ}C$ for 1 hr. However, both changed from (112) to (321) and (101), respectively, after 1800 hrs of storage at $55^{\circ}C/85%$ RH. The tensile stress of 8 MPa generated in as-plated sample was changed to a compression stress of 17 MPa after 2 days in room temperature storage. Due to the grain growth during postbake treatment, the WPB samples have more regular grains than the WOPB samples. In the as-plated sample, 0.32 ${\mu}m$ thickness of planar intermetallic compound (IMC) was observed. The IMCs in the WOPB and WPB samples had two distinct layers with large grains of $Cu_6Sn_5$ and with small grains of ${\eta}-Cu_{6.26}Sn_5$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.105-110
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• 2020

The global battery market is rapidly growing due to the development of vehicles(EV) and wireless electronic products. In particular logistics robots, which hielp to produce EVs, have attracted much interest in research in Korea Because logistics sites and factories operate continuously for 24 hours, the technology that can dramatically increase the operation time of the logistics equipment is rapidly developing, and various high-level technologies are required for the batteries used in. for example, logistics robots. These required technologies include those that enable rapid battery charging as well wireless charging to charge batteries while moving. The development of these technologies, however, result in increasing explosions and topical accidents involving rapid charging batteries These accidents due to the thermal shock caused by the heat generated during the charging of the battery cell. In this study, a performance evaluation of a heat dissipation design using infrared thermal imaging was performed on an energy storage systrm(Ess) applied with an internal heat conduction cooling method using a heating plate.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.151.2-151.2
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• 2014

Broadband impedances for the 3-GeV pohang light source-II (PLS-II) storage ring have been numerically estimated using a full three dimensional finite-difference time-domain code, CST particle studio. The total broadband impedance of all the vacuum components was estimated as 0.256 ohm, which is a small fraction of the total machine impedance budget.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.597-597
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• 2012

A simple solution-based method is developed to deposit crystalline ultrathin (2 nm) nickel hydroxide on vertically grown ZnO nanowires to achieve high specific capacitance and long-term life for flexible and wearable energy storage devices. Ultrathin crystalline $Ni(OH)_2$ enables fast and reversible redox reaction to improve the specific capacitance by utilizing maximum number of active sites for the redox reaction while vertically grown ZnO nanowires on wearable textile fiber effectively transport electrolytes and shorten the ion diffusion path. Under the highly flexible state $Ni(OH)_2$ coated ZnO nanowires electrode shows a high specific capacitance of 2150 F/g (based on pristine $Ni(OH)_2$ in 1 M LiOH aqueous solution with negligible decrease in specific capacitance after 1000 cycles. The synthesized energy-storage electrodes are easy-to-assemble which can provide unprecedented design ingenuity for a variety of wearable and flexible electronic devices.

• Journal of the Korean Electrochemical Society
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• v.13 no.3
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• pp.157-162
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• 2010

The electrodes comprising nano-sized $LiFePO_4$, carbon black and binder are prepared with two different Al current collectors. One is the generally used normal Al foil and the other is the chemically etched Al foil. Surface characteristics of each Al foil and electrochemical performance of the cathodes using each foil are investigated. The electrode from the etched Al foil exhibits better physical and electrochemical properties as compared to those of the normal Al foil because the etched Al foil has rough surface with sub-micron pores which improve the adhesion between the electrode materials and the substrate. The electrode on the etched Al foil has such a strong peel strength that the impedance is smaller than that of normal one. Indeed the $LiFePO_4$ electrode from the etched Al foil exhibits a better rate capability and remains intact even after storage for 1 week at the charged state at the elevated temperature $60^{\circ}C$.

• Transactions of the Society of Information Storage Systems
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• v.2 no.3
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• pp.163-168
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• 2006

Small form factor optical pickup (SFFOP) corresponding to BD specifications is strongly proposed for the next-generation portable storage device. In order to generate SFFOP, small sized optical pickup has been fabricated. We have developed a small sited optical pickup that is called the integrated optical pickup (IOP). The fabrication method of this system is mainly dependant on the use of the wafer based micro fabrication technology, which has been used in MEMS process such as photolithography, reactive ion etching, wafer bonding, and packaging process. This approach has the merits for mass production and high assembling accuracy. In this study, to generate the small sized optical pickup for high recording capacity, IOP corresponding to BD specifications has been designed and developed, including three main parts, 1) design, fabrication and evaluation of objective lens unit, 2) design and fabrication of IOP and 3) evaluation process of FES and TES.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.252-256
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• 2007

A series of spherical porous carbons were prepared via resorcinol-formaldehyde (RF) sol-gel polymerization in the presence of cationic surfactant (CTAB, cetyltrimethylammonium bromide), wherein the carbon sphere size was controlled by varying the CTAB introduction time after a pre-determined period of addition reaction (termed as "pre-curing"). The sphere size gradually decreases with an increase in the pre-curing time within the range of 30-150 nm. The carbons possess two types of pores; one inside carbon spheres (intra-particle pores) and the other at the interstitial sites made by carbon spheres (inter-particle pores). Of the two, the surface exposed on the former was dominant to determine the electric double-layer capacitor (EDLC) performance of porous carbons. As the intra-particle pores were generated inside RF gel spheres by gasification, the pore diameter was similar for all these carbons, thereby the pore length turned out to be a decisive factor controlling the EDLC performance. The charge-discharge voltage profiles and complex capacitance analysis consistently illustrate that the smaller-sized RF carbons deliver a better rate capability, which must be the direct result of facilitated ion penetration into shorter pores.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.183-186
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• 1992

Jindo Hongju is a traditional liquor in Korea. The characteristic of Hongju are its unique flavour and red color which is extracted from the root of gromwell (Lithospermum erythrorhizon). It is due to these color and flavour that Hongju attracts visual charm. However, the commercial value of Hongju is reduced because of the discoloration of red pigment during storage. Therefore, factors which cause the discoloration of red pigment and methods to prevent discoloration were investigated. The results obtained from this study are summarized as follows. The factors that cause the discoloration were visible light, temperature (beyond $40^{\circ}C$), pH (above 10) and inorganic ion ($Cu^{2-}$). Among all the additives added, Cystein (100 ppm) was the most effective inhibitor of pigment discoloration.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.9.1-9.1
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• 2008

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.288.1-288.1
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• 2008