• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.4
• /
• pp.383-391
• /
• 2011

The hot-stamping technique is used to manufacture high-strength parts by press forming by heating at a temperature above the Austenite transformation temperature and then rapid cooling. Boron steel, which contains a very small amount of boron, is one of the materials used for hot stamping. The purpose of this study is to show the microstructures and to investigate the mechanical properties under different heat-treatment conditions. The heat treatment of water quenching was conducted at the various temperatures and different elapsed times. These can be practical data useful when boron steels are used for hot stamping. Furthermore, the microstructures and mechanical properties of the spot-welded specimen with coatings and counterpart materials (SPRC 340, SPRC 590) is investigated in order to determine the welding characteristics of boron steel at different welding condition.

• Journal of the Semiconductor & Display Technology
• /
• v.13 no.3
• /
• pp.45-50
• /
• 2014

In this paper, we propose a super-junction MOSFET (SJ MOSFET) fabricated through a simple pillar forming process by varying the Si epilayer thickness and doping concentration of pillars using SILVACO TCAD simulation. The design of the SJ MOSFET structure is presented, and the doping concentration of pillar, breakdown voltage ($V_{BR}$) and drain current are analyzed. The device performance of conventional Si planar metal-oxide semiconductor field-effect transistor(MOSFET), Si SJ MOSFET, and SiGe SJ MOSFET was investigated. The p- and n-pillars in Si SJ MOSFET suppressed the punch-through effect caused by drain bias. This lead to the higher $V_{BR}$ and reduced on resistance of Si SJ MOSFET. An increase in the thickness of Si epilayer and decrease in the former is most effective than the latter. The implementation of SiGe epilayer to SJ MOSFET resulted in the improvement of $V_{BR}$ as well as drain current in saturation region, when compared to Si SJ MOSFET. Such a superior device performance of SiGe SJ MOSFET could be associated with smaller bandgap of SiGe which facilitated the drift of carriers through lower built-in potential barrier.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.3
• /
• pp.273-279
• /
• 1999

The home-made hot wall epitaxy (HWE) system was utilized for GaN epitaxial layer growth on the Si(001) substrate. It was appeared that GaN epilayer grow with mixed phase of Zinc blende and Wurtzite structure from photoluminescence (PL) and x-ray diffraction (XRD) analysis at the room temperature. We found that intial growth layer has Wurtzite structure from photoluminescence (PL) and x-ray diffractio (XRD) analyses at the room temperature. Wefound that initial growth layer has Wurtzite structure when initial deposition time, the temperature of substrate and source are 4 min, $720^{\circ}C$ and $860^{\circ}C$ respectively, and at the epi growth process GaN, epilayer was grown with relatively stable Wurtzite structure when the temperature of substrate and source are $1020^{\circ}C$ and $910^{\circ}C$ respectively.

• The Journal of Asian Finance, Economics and Business
• /
• v.8 no.2
• /
• pp.41-55
• /
• 2021

We examine the effects of the sustainability report (SURE) and investment decision on share price (SPRC). Explore whether the sustainability report changes the value-relevance of financial accounting variables indirectly. It is evident that the number of banks is only 12, which are all banks in Saudi Arabia, and we have included all of them in the final sample. Moreover, the same number of banks applied for the analysis concerning the accounting variables. This article utilizes a panel dataset from a sample of Saudis registered banks from the first quarter of 2014 to the last quarter of 2018. We utilize a balanced sample that contains all banks listed in Tadawul, 240 observations. Run GLM regression to tests the relationships. Findings exhibit that investors value the complementary disclosure of accounting information provided in SURE, and this disclosure produces a positive effect on SPRC. The SURE figure is robustly significant, suggesting that the market assigns a positive-significant correlation to the further information in the SURE. The indirect effects show that BPS×SURE is a positive-significant effect on SPRC, whereas EPS×SURE is positively-insignificant. The analysis shows that SURE's value relevance conforms through Saudis Banks, consistent with the hypothesis that diverse institutional perspectives probably influence the value-relevance of SURE.

• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.219-224
• /
• 2000

A research for development of composite body panel is in progress for lightening tare. Low specific weight LPMC (Low pressure molding compound) has advantages such as lightweight and resistance to dent and corrosion. In this study, tensile, bending and impact tests for the LPMC and SPRC35 (High tension steel plate) were carried out and compared. Although mechanical properties of SPRC35 are better than the LPMC, the LPMC satisfies basic requirements for car body panel. The high temperature exposed LPMC were degraded due to fiber-matrix debonding and deterioration of resin.

• Proceedings of the KIPE Conference
• /
• 2004.11a
• /
• pp.45-48
• /
• 2004

To improve the efficiency characteristics in the resonant converter using the contact-less power supply with the large air-gap and the long primary winding, this paper suggests the three-level series-parallel resonant converter(SPRC). The voltage gain characteristics of the proposed converter have the unit gain in a resonance frequency point of the series and parallel, and input voltage and current in the primary of SPRC are always In phase for the all equivalent load resistance because of the parallel resonant tank of the high impedance. The results are verified on the simulation based on the theoretical analysis and the 4kW experimental prototype.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.706-706
• /
• 2012

최근 세계적으로 홍수, 가뭄, 열파 등 기상재해가 빈발하여 소중한 생명과 막대한 재산피해가 발생하고 있으며 우리나라도 예외는 아니다. 특히 강원도 지역의 경우 태백산맥을 중심으로 산지가 많은 부분을 차지하고 있어 산악기후의 특성을 포함한 복잡한 기상현상을 나타내고 있다. 또한 강수량의 변화가 심한 편차를 나타내며 홍수와 가뭄이 반복되는 양상을 보이고 있다. 따라서 본 연구에서는 기상분석을 통한 강원도 지역에서 발생 가능한 홍수 및 가뭄의 피해원인 및 특성을 분석하고 지형특성과 유출특성 등을 고려한 우수저류조 저장기법을 제시하고자 한다. 이를 위해 SPRC(Source-Pathway-Receptor-Consequence) 기법을 적용해 강원도지역의 가뭄과 홍수특성을 고려한 우수저류조 설계요소를 도출하였고 그 적용성을 검토하였다. 추후 계속되는 연구결과를 통해 강원도의 지역특성을 반영한 LID 기반 최적 우수저류조 선정 의사결정지원체계를 구축하고자 한다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.3
• /
• pp.204-210
• /
• 2004

Most auto-body members fabricated by the sheet metal forming process. During this process the thickness and material properties of the sheet metal are changed with the residual stress and plastic strain. This paper deals with the material properties of the sheet metal at the high strain rate considering the pre-strain effect. Specimens are selected from sheet metals for outer panels and inner members, such as SPCEN, SPRC45E, SPRC35R and EZNCD. The specimens are prepared with the pre-strain of 2, 5 and 10 % by tensile elongation in Instron 5583, which could be equivalent to the plastic strain in sheet metal forming. High speed tensile tests are then carried out with the pre-stained specimens at the strain rate of 1 to 100/sec. The experimental result informs that the material properties are noticeably influenced by the pre-strain when the yield stress of the specimens is moderate as SPCEN, SPRC35R and EZNCD. The result also demonstrates that the ultimate tensile strength as well as the yield stress is increased as the amount of the pre-strain is increased.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.4
• /
• pp.495-502
• /
• 2014

Fast recovery diodes (FRDs) were developed using the $p^{{+}{+}}/n^-/n^{{+}{+}}$ epitaxial layers grown by low temperature epitaxy technology. We investigated the effect of electrostatic discharge (ESD) stresses on their electrical and switching properties using current-voltage (I-V) and reverse recovery time analyses. The FRDs presented a high breakdown voltage, >450 V, and a low reverse leakage current, < $10^{-9}$ A. From the temperature dependence of thermal activation energy, the reverse leakage current was dominated by thermal generation-recombination and diffusion, respectively, at low and high temperature regions. By virtue of the abrupt junction and the Pt drive-in for the controlling of carrier lifetime, the soft reverse recovery behavior could be obtained along with a well-controlled reverse recovery time of 21.12 ns. The FRDs exhibited excellent ESD robustness with negligible degradations in the I-V and the reverse recovery characteristics up to ${\pm}5.5$ kV of HBM and ${\pm}3.5$ kV of IEC61000-4-2 shocks. Likewise, transmission line pulse (TLP) analysis reveals that the FRDs can handle the maximum peak pulse current, $I_{pp,max}$, up to 30 A in the forward mode and down to - 24 A in the reverse mode. The robust ESD property can improve the long term reliability of various power applications such as automobile and switching mode power supply.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.9 no.5
• /
• pp.405-412
• /
• 2004

In this paper, Non-contact power supply(NCPS) with the long primary cable longer than 20m and the large air-gap between the primary and secondary of Non-Contacting Transformer(NCT) is presented. The NCT has a large leakage inductance bigger than its magnetizing inductance because it has low coupling, and it is not efficient for NCPS to transfer the primary energy to the secondary one. In order to improve this problem, the voltage-gain characteristics of the series resonant converter, the parallel resonant converter, and the series-parallel resonant converter are analyzed respectively. In addition, the experimental results of 10kW prototype the series-parallel resonant converter is presented.