• Journal of the Korean Magnetics Society
• /
• v.15 no.3
• /
• pp.198-201
• /
• 2005

We investigated the effects of organic additives on the properties of nickel-copper thin films prepared by electroplating. Compared with thin films fabricated by pure electrolyte only, the films utilizing organic additives show different crystalline orientations. With no alteration of plating conditions simply adding the organic materials changed the composition of copper and nickel. The concentration of nickel could be varied to $65-95\%$ depending on the species and concentration of the additives. The change of material property has contributed to the increase or decrease of the magnetoresistance.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1532-1535
• /
• 1996

Diamond-like carbon (DLC) films have been prepared by a widely-used plasma CVD with an rf (13.56MHz) plasma of $CH_4$ gas. The hydrogen incorporated in DLC films plays an important role of determining the film properties, but its exact role has not been clear. In this study, the effect of hydrogen on the film properties of DLC has been examined by adding the hydrogen gas to the $CH_4$ gas during deposition and by exposing the prepared film to the hydrogen plasma. As the content of additive hydrogen gas increases, the density and hardness of the film increase, but the growth rate decreases. The FT-IR spectroscopy results show that the number of C-H bonds decreases with increasing the hydrogen gas. Also, the variation in the position of "G" and "D" peaks due to additive hydrogen, which has been measured by the Raman spectroscopy, indicates of $sp^3$ fraction.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.4
• /
• pp.949-956
• /
• 2014

Recently, with the development of hardware and software technology related with image information delivery, the demand for various multimedia service has increased. But, the process of treating, sending, and storing image signals generates image degradation by various external causes. The main cause of image degradation is noise. image is mostly damaged by AWGN (additive white Gaussian noise). Therefore, there have been active researches on noise elimination. This paper, to reduce the effects of AWGN added to the image, suggests a noise-eliminating algorithm which is excellent in low-frequency and high-frequency characteristics in space. And, this paper, through simulation techniques, compared the result of the suggested algorithm with those of the existing methods. And, to evaluate the performance of it, PSNR (peak signal to noise ratio) was used.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.6
• /
• pp.538-548
• /
• 2003

We studied effects by Re$_2$O$_3$(R=Dy, Gd, Ho) addition on the properties of Mn-Zn ferrite. The doping concentration range from 0.05 wt% to 0.25 wt%. All samples were prepared by standard fabrication of ceramics. With increasing the rare earth oxides, specific density and initial permeability increased on the whole. But, the tendencies such as upper result had the measured value on limitation and characteristics saturated or decreased properties after that. In case of excessive addition of additive beyond some level, initial permeability properties of ferrite have gone down in spite of anomalous grain. With increasing the content of additive, both the real and imaginary component of complex permeability and the magnetic loss (tan$\delta$) increased. Because the increased rate of real component had higher than imaginary component, magnetic loss increased none the less for increasing the real component related with magnetic permeability. But, the magnetic loss of ferrite doped with the rare earth oxides was lower than that of Mn-Zn ferrite at any rate. The small amount of present rare earth oxides in Mn-Zn ferrite composition led to enhancement of resistivity in bulk, and more so in the grain boundary. It was seem to be due to the formation of mutual reaction such as between iron ions and rare earth element ions.

• Journal of the Korean Society of Visualization
• /
• v.13 no.1
• /
• pp.9-14
• /
• 2015

There have been many attempts to reduce the cost of transportation. Especially, drag reduction of heavy vehicles has enormous influence on energy saving by reducing the driving power of the vehicles. In this study, the effects of drag-reducing additive devices such as side skirt, boat tail and cab-roof fairing on the drag reduction of a 5 ton truck model were experimentally investigated. The aerodynamic performance of these flow-control devices attached to heavy vehicle was evaluated through wind tunnel test. In addition, flow patterns around the truck model were visualized by using smoke tube method. The drag coefficient is reduced by up to 5.7%, 7.16% and 22.2% by the side skirt, boat tail and cab-roof fairing, respectively. The interactive effect of the side skirt and boat tail was also investigated.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.4
• /
• pp.409-415
• /
• 2016

Magnetite particles were synthesized by co-precipitation of water-soluble 밀 스케일-derived precursor by various concentrations of (0.5, 0.67, 1, 2 N) NaOH and (0.6, 0.8, 1.2, 2.4 N) $NH_4OH$. It is theoretically known that as the concentration of the alkaline additive used in iron oxide synthesis increases, the particle size distribution of that iron oxide decreases. This trend was observed in both kind of alkaline additive used, NaOH and $NH_4OH$. In addition, the magnetite synthesized in NaOH showed a relatively smaller particle size distribution than magnetite synthesized in $NH_4OH$. Crystalline phase of the synthesized magnetite were determined by X-ray diffraction spectroscopy(XRD). The particles were then used as an adsorbent for phosphate(P) removal. Phosphorus adsorption was found to be more efficient in NaOH-based synthesized magnetite than the $NH_4OH$-based magnetite.

• Corrosion Science and Technology
• /
• v.10 no.4
• /
• pp.143-150
• /
• 2011

Copper electroplating has been applied to various fields such as decorative plating and through-hole plating. Technical realization of high strength copper preplating for wear-resistant tools and molds in addition to these applications is the aim of this work. Brighters and levelers, such as MPSA, Gelatin, Thiourea, PEG and JGB, were added in copper sulfate electrolyte, and the effects of these organic additives on the hardness were evaluated. All additives in this work were effective in increasing the hardness of copper electrodeposits. Thiourea increased the hardness up to 350 VHN, and was the most effective accelarator in sulfate electrolyte. It was shown from the X-ray diffraction analysis that preferred orientation changed from (200) to (111) with increasing concentration of organic additives. Crystallite size decreased with increasing concentration of additive. Hardness was increased with decreasing crystallite size, and this result is consistent with Hall-Petch relationship, and it was apparent that the hardening of copper electrodeposits results from the grain refining effect.

• Journal of the Korean Ceramic Society
• /
• v.50 no.6
• /
• pp.416-422
• /
• 2013

Cullet-loess tile bodies are successfully fabricated using cullet, loess, hollow microspheres, and sintering additives (borosilicate glass frit, boric acid, or fumed silica) as starting materials. The effects of the additive composition and sintering temperature on the sintered density and flexural strength of the cullet-loess tile bodies are investigated. The sintered density of the cullet-loess tile bodies increases with an increase in the sintering temperature as a result of the enhanced densification of pore walls through the viscous flow of a liquid phase formed from the glass frit and sintering additives. The flexural strength of the cullet-loess tile bodies increases with increases in the sintering temperature and the cullet content in the starting composition. A maximal flexural strength of 40 MPa is obtained in cullet-loess tile bodies sintered with glass frit at $800^{\circ}C$ in air.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.9
• /
• pp.1985-1997
• /
• 1997

This paper proposed a regularized iterative image restoration by using method of conjugate gradient. Compared with conventional iterative methods, method of conjugate gradient has a merit to converte toward a solution as a super-linear convergence speed. But because of those properties, there are several artifacts like ringing effects and the partial magnification of the noise in the course of restoring the images that are degraded by a defocusing blur and additive noise. So, we proposed the regularized method of conjugate gradient applying constraints. By applying the projectiong constraint and regularization parameter into that method, it is possible to suppress the magnification of the additive noise. As a experimental results, we showed the superior convergence ratio of the proposed mehtod compared with conventional iterative regularized methods.

• Biomaterials and Biomechanics in Bioengineering
• /
• v.3 no.1
• /
• pp.1-14
• /
• 2016

Well-ordered porous materials are very promising in orthopedics since they allow tailoring the mechanical properties. Finite element (FE) analysis is commonly used to evaluate the mechanical behavior of well-ordered porous materials. However, FE results generally differ importantly from experimental data. In the present article, three types of manufacturing irregularities were characterized on an additive manufactured porous titanium sample having a simple cubic unit-cell: strut diameter variation, strut inclination and fractured struts. These were included in a beam FE model. Results were compared with experimental data in terms of the apparent elastic modulus (Eap) and apparent yield strength (SY,ap). The combination of manufacturing irregularities that yielded the closest results to experimental data was determined. The idealized FE model resulted in an Eap one order of magnitude larger than experimental data and a SY,ap almost twice the experimental values. The strut inclination and fractured struts showed the strongest effects on Eap and SY,ap, respectively. Combining the three manufacturing irregularities produced the closest results to experimental data. The model also performed well when applied to samples having different structural dimensions. We recommend including the three proposed manufacturing irregularities in the FE models to predict the mechanical behavior of such porous structures.