• Bulletin of the Korean Chemical Society
• /
• v.28 no.11
• /
• pp.1996-2002
• /
• 2007

The redox behavior of a [Ni6(μ3-Se)2(μ4-Se)3(Fe(η 5-C5H4P-Ph2)2)3] (= [Ni-Se-dppf], dppf = 1,1-bis(diphenylphosphino) ferrocene) cluster was studied using platinum (Pt) and glassy carbon electrodes (GCE) in nonaqueous media. The cluster showed electrochemical activity at the potential range between +1.6 and ?1.6 V. In the negative region (0 to ?1.6 V), the cluster exhibited two-step reductions. The first step was one-electron reversible, while the second step was a five-electron quasi-reversible process. On the other hand, in the positive region (0 to +1.6 V), the first step involved one-electron quasi-reversible process. The applicability of the cluster was found towards the electrocatalytic reduction of CO2 and was evaluated by experiments using rotating ring disc electrode (RRDE). RRDE experiments demonstrated that two electrons were involved in the electrocatalytic reduction of CO2 to CO at the Se-Ni-dppf-modified electrode.

• Journal of the Korean Ceramic Society
• /
• v.55 no.6
• /
• pp.562-569
• /
• 2018

We propose an economic and facile method for the preparation of silica nanoparticles through a two-step process utilizing chlorosilane residues. Mixed chlorosilane residue was alcoholized with absolute ethanol as a first step to form tetraethoxysilane (TEOS). The TEOS was then utilized as a silicon source to synthesize silica nanoparticles in a sol-gel method. The alcoholysis process was designed and optimized utilizing the Taguchi experimental design method and the yield of TEOS was as high as 82.2% under optimal synthetic conditions. Similarly, the Taguchi method was also utilized to study the effects of synthesis factors on the particle size of silica nanoparticles. The results of statistical analysis indicate that the concentration of ammonia has a greater influence on particle size compared to the mass fractions of TEOS and polyethylene glycol (4.6% and 9.7%). The purity of the silica particles synthesized in our experiments is high, but the specific surface area and pore volume are small.

• Transactions of Materials Processing
• /
• v.14 no.9 s.81
• /
• pp.791-797
• /
• 2005

Extensive width reduction of slabs is an important technology for achieving continuous production between the steelmaking and hot rolling processes. However, the vertical horizontal rolling process has many disadvantages, e.g., large width deviations and less efficient width reduction. This study was carried out to investigate the deformation of slab by sizing press with two steps die. To do it, dog-bone and camber are discussed in width sizing process considering the deformation behavior according to the deviation of anvil velocity and the deviation of initial slab temperature. In this paper, the various causes of the sizing press phenomena are mentioned for the purpose of understanding of rolling conditions. As a result, the optimal anvil shape having a minimum-forming load is obtained by FE-simulation and ANN.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.2001-2005
• /
• 2005

The tensile test is generally used to measure mechanical properties with conventional fracture test. This test is extremely certain method to measure Young's modulus, yield strength, tensile strength and so on. ASTM, by international standard, prescribes two classes of tensile tests in tubular products. One is method that specimens aren't done by any process with Tube-shape. The other is that specimens are made on process for C-shape. In this paper, we would like to present the new-shape specimens for the tensile test. The presented specimen's shape is that put two pieces of C-shape specimens together. Besides a load point and a support point are fixed like Tube-shape specimens. This shape of specimen has a difference that existing specimen is made on one-step process out this specimen is made on two-step process. This shape is considered that stress concentration phenomenon occurs at the reduced section if a specimen is made on one step process.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.3
• /
• pp.55-60
• /
• 2020

The recent semiconductor packaging technology is evolving into a high-performance system-in-packaging (SIP) structure, and copper-to-copper bonding process becomes an important core technology to realize SIP. Copper-to-copper bonding process faces challenges such as copper oxidation and high temperature and high pressure process conditions. In this study, the bonding interface quality of low-temperature copper-to-copper bonding using a two-step plasma treatment was investigated through quantitative bonding strength measurements. Our two-step plasma treatment formed copper nitride layer on copper surface which enables low-temperature copper bonding. The bonding strength was evaluated by the four-point bending test method and the shear test method, and the average bonding shear strength was 30.40 MPa, showing that the copper-to-copper bonding process using a two-step plasma process had excellent bonding strength.

• Proceedings of the IEEK Conference
• /
• 2000.06b
• /
• pp.274-277
• /
• 2000

Thin Film Transistor(TFTs) were fabricated from poly-Si crystallized by a two-step annealing process on glass substrates. The combination of low-temperature(500$^{\circ}C$) Metal-Induced Lateral Crystallization(MILC) furnace annealing and high -temperature (700$^{\circ}C$) rapid thermal annealing leads to the improvement of the material quality The TFTs measured with this two-step annealing material exhibit better characteristics than those obtained by using conventional MILC furnace annealing.

• Communications for Statistical Applications and Methods
• /
• v.20 no.5
• /
• pp.377-385
• /
• 2013

We consider a compound Poisson risk model in which the premium rate changes when the surplus exceeds a threshold. The explicit form of the ruin probability for the risk model is obtained by deriving and using the overflow probability of the workload process in the corresponding M/G/1 queueing model.

• Journal of the Semiconductor & Display Technology
• /
• v.9 no.3
• /
• pp.5-9
• /
• 2010

Recently, the important issues of solar cell are low cost and high efficiency. Making low cost and high efficiency solar cell, there are many effects to development of inexpensive wafer, simplify process and improve optical, electrical properties. In this the study, the 2 step texturing method using micro blaster was developed to decrease reflection of incident lights. Air bridge electrode structure is suggested to expand the effective surface area and decrease the series resistance of finger electrode. The effects of 1 step texturing and 2 step texturing by micro blaster are compared. Reflectance of 1 step and 2 step texturing are measured 28.7% and 25.5%, respectively. The reflectance of 2 step texturing sample is lower about 3.2% than 1 step textured sample.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.4
• /
• pp.16-21
• /
• 2011

This paper described an analysis of dynamic mechanism for the industrial two-step folding automatic door using commercial software packages. Two modeling types of operating on the guide rail, the sliding one and the rolling, were adopted to investigate effects of impact force when the door ascends the guide rail. The magnitude of impact force was found very peaklike large over an initial duration of the door's moving up. The amount of damping coefficient for alleviating this shock was controlled to such a moderate degree that the operating conditions can be obtained for the purpose of design. Moreover the behavior of both dynamic stress and deformation were observed for acquirement of structural reliabilities of the combined guide rail and rolling mechanism. This research will be a very useful tool in the near future for the dynamic analysis of the multi-step folding automatic door.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.432-435
• /
• 2005

Extensive width reduction of slabs is an important technology to achieve continuous production between the steelmaking and hot rolling processes. Conventionally, a vertical roll process has been used to achieve extensive width reduction. However, it is impossible to avoid the defects such as dog-bone, fish tail and camber. The deformation behavior in the width sizing process is more favorable than that in conventional vertical rolling edger, i.e. the material better flows toward the center of slab. This study is carried out to investigate the deformation of slab by two-step sizing press. The FE-simulation is utilized to predict plastic deformation mode in compression by a sizing press of slabs far hot rolling. In this paper, the various causes of the asymmetrical rolling phenomena are mentioned for the purpose of understanding of rolling conditions. Analytical results of slab-deformation by sizing press are presented below in this study.