• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.9
• /
• pp.1626-1631
• /
• 2010

The characteristics of electric current for the voltaic cell are important for electric power applications. In this paper, an electrical equivalent model consist of three resisters and a capacitance for the Cu/NaCl solution/Zn electrochemical cell is proposed. The capacitance which exists in the Zn electrode/electrolytic interface increased according to Zn electrode area, but cannot affect almost in electric current. Complex impedance plot was used to analysis the interface effect for Zn/electrolyte. This result shows that the interface is similar with the electric transmission line. The short current measurements were conducted to investigate the effects of hydrogen peroxide, the watery sulfuric acid and NaCl aqueous solution. As the hydrogen peroxide increased, the electric current increased because the hydrogen gas being converted with the water. Also electric current increased significantly with increase of the hydrogen ion with the watery sulfuric acid and increased with increase of $Na^+$ ion and $Cl^-$ion in the NaCl electrolyte.

• Journal of the Korean Society of Safety
• /
• v.23 no.4
• /
• pp.25-29
• /
• 2008

Recently, new functionally graded material(FGM) that has a spatial variation in composition and properties is developed because of its good quality. This material yields the demands for resistance to corrosion and high temperature in turbine blade, wear resistance as in gears and high strength machine parts. Especially coating treatment in FGM surface brings forth a mechanical weak at the interface due to discontinuous stress resulting from a steep material change. It often, leads cracks or spallation in a coating area around an interface. The behavior of propagation cracks in FGMs was here investigated. The interface stresses were reduced because of graded material properties. Also graded material parameter with exponential equation was founded to influence the stress intensity factor. And the resistance curve with FGM coating was slightly increased.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.756-761
• /
• 1999

The objective of this study is to develop finite element analysis technique to predict the strength reduction of deteriorated reinforced concrete beams and their strengthening capacity. In order to consider the effect of rebar corrosion, a tension stiffening model is proposed and area reduction of rebars due to corrosion is considered. For the analysis of strengthened deteriorated RC beams, one dimensional truss element and an interface element are introduced for models of the strengthening composite and the interface between concrete and composite to simulate delamination or discontinuous behavior at the interface. Then, analyses for deteriorated RC beams strengthened with glass fiber reinforced epoxy panel (GFREP) are carried out to predict both flexural failure and plate-end delamination failure. Finally, analysis results are verified with experimental results.

• Proceedings of the IEEK Conference
• /
• 2002.07b
• /
• pp.1304-1307
• /
• 2002

In this paper, we describe the structure and the test results of a Bluetooth baseband module we have developed. The module has a distributed buffer, i.e. FIFO, for data stream. Bus interface of the module is designed on the basis of interface of microprocessor widely used and the external interface is designed to consider chips connected directly. Since the module performs as many hardware efficient tasks as possible, processing load of microprocessor is very small. It can also be controlled either by software or by hardware for flexibility. The fully synthesizable baseband module was fabricated in a $0.25\mu\textrm{m}$ CMOS technology occupying $2.79\times2.8{\textrm{mm}^2}$ area. And an FPGA implementation of this module is tested for file and bit-stream transfers between PCs.

• Proceedings of the IEEK Conference
• /
• 1999.06a
• /
• pp.1049-1052
• /
• 1999

We present a use. interface(UI) simulator for developing a mobile phone. This simulator consists of 3 major modules: Graphic Tool Editor, User Interface Software(UI), and Network Command Processor(NCP). The Graphic Tool Editor can design a virtual mobile terminal. The NCP sends a command to the phone and then receives its status from the phone after completion of the command. We can add or modify lots of features easily to the phone using the UI module. These modules can interact each other by sharing the common area in the memory. By doing so, these modules can exchange their status and data to operate in real-time. We have designed and tested a virtual prototyping phone for the LGP 3200 manufactured by LGIC by using the simulator. Through a series of experiment, we have believed that our virtual prototyping interactive simulator can do shorten its development and testing cycle by applying it in the early design phase.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.12
• /
• pp.4392-4396
• /
• 2011

Porous silicon with a complex network of nanopores is utilized for photoelectrochemical energy conversion. A novel electroless Pt deposition onto porous silicon is investigated in the context of photoelectrochemical hydrogen generation. The electroless Pt deposition is shown to improve the characteristics of the PS photoelectrode toward photoelectrochemical $H^+$ reduction, though excessive Pt deposition leads to decrease of photocurrent. Furthermore, it is found that a thin layer (< 10 ${\mu}m$) of porous silicon can serve as anti-reflection layer for the underlying Si substrate, improving photocurrent by reducing photon reflection at the Si/liquid interface. However, as the thickness of the porous silicon increases, the surface recombination on the dramatically increased interface area of the porous silicon begins to dominate, diminishing the photocurrent.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.03a
• /
• pp.140-143
• /
• 1997

The present study is concerned with the hydrostatic extrusion process of copper-clad aluminium bar to investigate the basic flow characteristics. Considering the bonding mechanism of bi-metal contact surface as cold pressure welding, the normal pressure and the contact surface expansion are selected as process parameters governing the bonding condition. The critical pressure required for the bonding at the interface is obtained by solving a "local extrusion" using a slip line meyhod. A viscoplastic finite element method is used to analyze the steady state extrusion process. The boundary profile of bi-metal rod is predicted by tracking a particle path adjacent to interface surface. The variations of contact surface area and the normal pressure along the interface profile are predicted and compared to those by experiments.

• Progress in Superconductivity and Cryogenics
• /
• v.15 no.2
• /
• pp.48-51
• /
• 2013

The thermal contact resistance (TCR) is one of the important components in the cryogenic systems. Especially, cryogenic measurement devices using a cryocooler can be affected by TCR because the systems have to consist of several metal components in contact with each other for heat transferring to the specimen without cryogen. Therefore, accurate measurement and understanding of TCR is necessary for the design of cryogenic measurement device using a cryocooler. The TCR occurs at the interface between metals and it can be affected by variable factors, such as roughness of metal surface, contact area and contact pressure. In this study, we designed TCR measurement system at various temperatures using a cryocooler as a heat sink and used steady state method to measure the TCR between metals. The copper is selected as a specimen in the experiment because it is widely used as a heat transfer medium in the cryogenic measurement devices. The TCR between Cu and Cu is measured for various temperatures and contact pressures. The effect of the interfacial materials on the TCR is also investigated.

• Journal of the Korean Applied Science and Technology
• /
• v.32 no.4
• /
• pp.661-668
• /
• 2015

The surface rheological properties of polymer monolayer show complicated non-linear viscoelastic flow phenomena when they are subjected to spreading flow. These spreading flow properties are controlled by the characteristics of flow units. The kinetics of the formation of an interfacial film obtained after spreading poly(diisobutylene maleic acid) at air-water interface were studied by measuring of the surface pressure with time. The experimental data were analyzed theoretically according to a nonlinear surface viscoelastic model. The values of dynamic modulus, static modulus, surface viscosities and rheological parameters in various area/ monomer were obtained by appling experimental data to the equation of nonlinear surface viscoelastic model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.11a
• /
• pp.198-201
• /
• 1994

Stability improvement of fragile LB films was attempted by polyion complexation of monolayers at the air-water interface and crosslinking of the resulting LB films. The spreading polymers were synthesized by radical copolymerization of monoalkyl itaconate with oligoethyleneglycol methyl vinylether, and poly(allylamine) was employed as the subphase polymer. Formation and characteristic of the monolayers were comfirmed by surface pressure-area($\pi$-A) isotherms. The two different polymers formed polyion-complexed monolayer through the formation of carboxylate/ammonium salt at the air-water interface. Y-type deposition occurred on solid substrates, and the transfer ratio was over 0.7. Pores (diameter, 0.1$\mu\textrm{m}$) of a membrane filter could be covered by polyion-complexed 6 layers. Interactions of the polymers with metal ions were investigated of the air-water interface and in the LB films. The structure change and macroscope morphology of the LB films were confirmed by FT-lR and SEM, respective1y.