• Corrosion Science and Technology
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• v.9 no.1
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• pp.16-19
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• 2010

Application of ultra-high strength steel sheets is one of the most important methods to satisfy weight reduction and crash safety of a vehicle. Recently, there has been a trend to apply ultra-high strength steel sheets widely to underbody parts in which corrosion resistance is required. In this work, ultra-high strength galvannealed steel sheets with a tensile strength of 1180 MPa were developed. Newly developed ultra-high strength galvannealed steel sheets have comparable properties, such as mechanical properties, spot weldability, crashworthiness and adhesion of coatings, to conventional steel sheets.

• International Journal of High-Rise Buildings
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• v.2 no.2
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• pp.105-113
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• 2013

Recent studies proved turbulent flow properties in high-rise building models differ from those in low-rise building models by comparing turbulent statistics. Although it is important to understand the flow characteristics within and above high-rise building models in the study of urban environment, it is still unknown and under investigation. For this reason, we performed wind tunnel experiment using Particle Image Velocimetry (PIV) to investigate and identify the turbulent flow properties and characteristic flow patterns in high-rise building models. In particular, we focus on instantaneous flow field near the canopy and extracted flow field when homogeneous flow field were observed. As a result, six characteristic flow patterns were identified and the relationship between these flow patterns and turbulent organized structure were shown.

• Phonetics and Speech Sciences
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• v.2 no.4
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• pp.59-65
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• 2010

In this paper, we investigate acoustic characteristics of Korean /s/ when it is followed by both a high front and a round segment regardless of their order to one another. We show that Korean /s/ in this environment has characteristics of a labio-palatalized segment, being affected by both a high front and a round segment if they occur within the domain of a syllable. In the experiment, we show that Korean /s/ before a high front and a round segment shows a spectral shape different from that in other environments. Specifically, it is different from /s/ before a high front segment only, showing peaks around 2.5 kHz. Furthermore, it shows a rapid decrease of amplitude in 4-5 kHz, and sometimes another plateau of high peaks in 5-6 kHz. We also examined center of gravity frequency and band energy difference. Based on the results of this experiment, we argue that Korean /s/ is affected by the following segments within the domain of coarticulation, a syllable and that the degree of coarticulation is different from language to language.

• Journal of the Korean Ceramic Society
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• v.53 no.5
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• pp.548-556
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• 2016

Recently, porous alumina-based ceramics have been extensively applied in the semi-conductor and display industries, because of their high mechanical strength, high chemical resistance, and high thermal resistance. However, the high electrical resistance of alumina-based ceramics has a negative effect in many applications due to the generation of static electricity. The low electrical resistance and high air permeability are key aspects in using porous alumina-based ceramics as vacuum chucks in the semi-conductor industry. In this study, we tailored the pore structure of porous alumina-based ceramics by adjusting the mixing ratio of the starting alumina, which has different particle sizes. And the electrical resistance was controlled by using chemical additives. The characteristics of the specimens were studied using scanning electron microscopy, mercury porosimetry, capillary flow porosimetry, a universal testing machine, X-ray diffraction, and a high-resistance meter.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.487-488
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• 2015

New inverter motor drive systems consume 30%~50% less energy compared to existing motor drive systems. For inverter motor drive systems, the development of a 1200V high side driver is critical. This paper presents an advanced 1200V high side driver with low power consumption and high ruggedness. This solution implements a high voltage level shifter which consumes low power by adding a clamped VGS LDMOS driver to the conventional short pulse generator. Moreover, this paper proposes a highly rugged 1200V LDMOS which improves SOA by limiting the hole current. This paper could be applied to smart power modules used for HVAC (heating, ventilation, and airconditioning) and industrial inverters. Consequently, this paper will provide design engineers with an understanding of how they can make a significant contribution to worldwide energy savings.

• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.236-240
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• 2004

Autohydrogenotrophic denitrification of high nitrate concentration contaminated wastewater in a batch-scale biofilm reactor has been investigated. High nitrate concentration decreased as pH increased from 7.01 to 9.45. The high nitrate concentrations continuously decrease from $150mg.l^{-1}$ to $0mg.l^{-1}$. Nitrite concentrations increase at about two-thirds way through the denitrification process and thereafter it decreases with time. Autohydrogenotrophic denitrification of high nitrate concentration is passible to use drinking water as well as wastewater, and to deal with wastewater treatment by hetrotrophic denitrification.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.67-71
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• 2007

The electrical insulation design of 600 kJ conduction cooled high-Tc superconducting magnetic energy storage (SMES) have been studied in this paper. The high voltage is applied to both ends of magnet of high-Tc SMES by quench or energy discharge. Therefore. the insulation design of the high voltage needs for commercialization. stability. reliability and so on. In this study. we analyzed the insulation composition of a high-Tc SMES. and investigated about the insulation characteristics of the materials such as Kapton. AIN. $Al_2O_3$. GFRP and vacuum in cryogenic temperature. Base on these results. the insulation design for 600 kJ conduction cooled high-Tc SMES was performed.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.331-338
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• 2005

The rapid advances in high power light sources and arrays as encountered in incandescent lamps have induced dramatic increases in die heat flux and power consumption at all levels of high power LED packaging. The lifetime of such devices and device arrays is determined by their temperature and thermal transients controlled by the powering and cooling, because they are usually operated under rough environmental conditions. The reliability of packaged electronics strongly depends on the die attach quality, because any void or a small delamination may cause instant temperature increase in the die, leading sooner or later to failure in the operation. Die attach materials have a key role in the thermal management of high power LED packages by providing the low thermal resistance between the heat generating LED chips and the heat dissipating heat slug. In this paper, thermal transient characteristics of die attach in high power LED package have been studied based on the thermal transient analysis using the evaluation of the structure function of the heat flow path. With high power LED packages fabricated by die attach materials such as Ag paste, solder paste and Au/Sn eutectic bonding, we have demonstrated characteristics such as cross-section analysis, shear test and visual inspection after shear test of die attach and how to detect die attach failures and to measure thermal resistance values of die attach in high power LED package. From the structure function oi the thermal transient characteristics, we could know the result that die attach quality of Au/Sn eutectic bonding presented the thermal resistance of about 3.5K/W. It was much better than those of Ag paste and solder paste presented the thermal resistance of about 11.5${\~}$14.2K/W and 4.4${\~}$4.6K/W, respectively.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.5687-5692
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• 2013

Type 2 diabetes mellitus (T2DM) has contributed to advanced breast cancer development over the past decades. However, the mechanism underlying this contribution is poorly understood. In this study, we determined that high glucose enhanced proteasome activity was accompanied by enhanced proliferation, migration and invasion, as well as suppressed apoptosis, in human breast cancer MCF-7 cells. Proteasome inhibitor bortezomib (BZM) pretreatment mitigated high glucose-induced MCF-7 cell growth and invasion. Furthermore, high glucose increased protein kinase C delta ($PKC{\delta}$)-phosphorylation. Administration of the specific $PKC{\delta}$ inhibitor rottlerin attenuated high glucose-stimulated cancer cell growth and invasion. In addition, $PKC{\delta}$ inhibition by both rottlerin and $PKC{\delta}$ shRNA significantly suppressed high glucose-induced proteasome activity. Our results suggest that $PKC{\delta}$-dependent ubiquitin proteasome system activation plays an important role in high glucose-induced breast cancer cell growth and metastasis.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.141-147
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• 2010

In this study, high-k oxide films like $Al_2O_3$, $TiO_2$, $HfO_2$ were deposited on Si, $SiO_2$/Si, GaAs wafers, and then the thermal conductivity was measured by using thermo-reflectance method which utilizes the reflectance variation of the film surface produced by the periodic temperature variation. The result shows that high-k oxide films with 50 nm thickness have high thermal conductivity of 0.80~1.29 W/(mK). Therefore, effectively dissipate the heat generated in the electric circuit such as CMOS memory device, and the heat transfer changes according to the micro grain size.