• Journal of the Korean Chemical Society
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• v.11 no.4
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• pp.138-142
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• 1967

The electrode reduction velocities of Zn, Ni and Co ions at DME in various supporting electrolytes and temperatures were measured by Randles' method. The values for Zn ions agreed with Randles' values within 20%. As mentioned in the auther's previous paper, the observed values of Ni and Co ions were considered to be reasonable. In the present work the curves log y vs. log z for the various metals in the range of 20~35$^{\circ}C$ were obtained.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.231-234
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• 2001

Shearing, including blanking, trimming, piercing, etc, is one of the most frequently used processes in sheet metal manufacturing. In this paper, an individual set of tooling with an in-die sensor was designed and precisely fabricated to carry out the experiment for the shearing process investigation. Through various experiments, it has been examined the influence of process parameters such as clearance, edge material properties and pad configuration. Since the tension between the part and the scrap increases when the clearance increases, the clearance should be selected properly in order to reduce the burr height. Also removal of the lower pad makes the sheared surface worse and the shearing system unstable. The shearing force increases when the clearance decreases and the friction of the tooling material decreases. Dynamic reaction force is also important to obtain the fine sheared surfaces.

• Korean Membrane Journal
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• v.1 no.1
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• pp.73-80
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• 1999

The removal of trace chlorinated and aromatic hydrocarbons from water by a pervaporation technique has been carried out through poly (dimethylsiloxane) membrane which had been fabricated by the addition crosslinking reaction. This study dealt with the swelling and permeation behaviors of the PDMS membranes with dichloroethane trichloroethane and toluene aqueous solutions. The swelling ratio in the toluene aqueous solution was much higher than those in the chloroethane solutions at all of the operating temperatures and concentrations. The solubility parameter theory was introduced to interpret the affinity between permeates and a membrane material and in all cases this approach seemed to be proper. It was suggested that the existence of water clusters in the membrane due to the hydrophobic characteristics of the membrane made the size of the permeating water larger resulting in suppressing water permeation and increasing enrichment of the organic components. The permeation behaviors at different membrane thicknesses were indirectly interpreted in terms of the effect of concentration polarization.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.7
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• pp.1049-1058
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• 1990

Mathematical modeling equations of a parallel plate type reactor were obtained in the PECVD process in preparing hydrogenated amorphous silicon. Velocity profiles, temperature profiles and concentration profiles in the reactor were calculated from the model. The theoretical approach was attempted to obtain the deposition rate and film uniformity at different operating conditions by calculating RF discharge parameters and establishing the reaction mechanisms of a-Si:H thin film. The modelling equations are solved by a finite difference method with control volume balance. The mean electrom energy in discharge was applied to model simulation parameter. The magnitudes of the predicted deposition rate are in good aggrement with those of experiment. The results of computer simulation shows that uniform deposition profiles can.

• Journal of the Korean Ceramic Society
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• v.25 no.2
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• pp.184-190
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• 1988

ZrN powder was prepared from the powder mixture of ZrCl4 and Al by the halogenide process in nitrogen gas flow (100-150ml/min) at the temperatures from 200$^{\circ}$to 1050$^{\circ}C$. ZrN powder was formed about 600$^{\circ}C$ and in the slow nitriding reaction, however, an intermediate product of Al3Zr was formed. The fine powder (0.1-10$\mu\textrm{m}$) of single phase ZrN was obtained at 1050$^{\circ}C$ after 1 hour. The lattice parameter and crystallite size of ZrN were 4.5787A and 360A, respectively. According to SEM observation, the particles were apt to agglomerates. The apparent activation energy for the formation of ZrN was approximately 13.2kcal/mole(750$^{\circ}$-1000$^{\circ}C$).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.34-38
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• 1999

In this study, molybdenum thin films were etched with the various Cl$_2$/(Cl$_2$+SF$_{6}$) gas mixing ratio in an magnetically enhanced reactive ion etching(MERIE) by the etching parameter such as rf power of 185 watts, chamber pressure of 40 mTorr and B-field of 80 gauss. The etch rate was 150 nm/min under Cl$_2$/(Cl$_2$+SF$_{6}$) gas mixing ratio of 0.25. At this time, the selectivity of Mo to SiO$_2$, photoresist were respectively 0.94, 0.50. The surface reaction of the etched Mo thin films was investigated with X - ray photoelectron spectroscopy (XPS).PS).

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1016-1022
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• 2014

The kinetic studies on the reactions of O-methyl N,N-diisopropylamino phosphonochloridothioate with X-anilines and X-pyridines have been carried out in acetonitrile. The free energy relationship with X in the anilines exhibits biphasic concave upwards with a break region between X = (H and 4-F), giving unusual negative ${\beta}_X$ and positive ${\rho}_X$ values with weakly basic anilines. The unusual phenomenon is rationalized by isokinetic relationship. A stepwise mechanism with a rate-limiting leaving group departure from the intermediate is proposed based on the selectivity parameter and variation trend of the deuterium kinetic isotope effects with X. The free energy relationship with X in the pyridines exhibits biphasic concave upwards with a break point at X = 3-MeO. A concerted mechanism is proposed based on relatively small ${\beta}_X$ value, and frontside and backside nucleophilic attack are proposed with strongly and weakly basic pyridines, respectively.

• Journal of applied mathematics & informatics
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• v.28 no.5_6
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• pp.1035-1054
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• 2010

We consider a mixed type singularly perturbed one dimensional elliptic problem with discontinuous source term. The domain under consideration is partitioned into two subdomains. A convection-diffusion and a reaction-diffusion type equations are posed on the first and second subdomains respectively. Two hybrid difference schemes on Shishkin mesh are constructed and we prove that the schemes are almost second order convergence in the maximum norm independent of the diffusion parameter. Error bounds for the numerical solution and its numerical derivative are established. Numerical results are presented which support the theoretical results.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.49-54
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• 2005

Linear metro with single sided linear induction motor is applied to the urban transit system because of non adhesion drive. But linear induction motor is required to reduce the energy consumption to maximize efficiency of LIM. In this paper, design requirements such as pole pitch, motor length, air gap, overhang length and the material of secondary sheet are investigated as major parameter of SLIM. It is effective for increasing the efficiency to adopt the copper reaction plate and decrease the mechanical air gap as small as possible.

• Steel and Composite Structures
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• v.13 no.2
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• pp.109-122
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• 2012

An efficient and accurate algorithm is proposed to evaluate the reliability of cable-stayed bridges accounting for soil-pile interaction. The proposed algorithm integrates the finite-element method and the response surface method. The finite-element method is used to model the cable-stayed bridge including soil-pile interaction. The reliability index is evaluated based on the response surface method. Uncertainties in the superstructure, the substructure and load parameters are incorporated in the proposed algorithm. A long span steel cable-stayed bridge with a main span length of 1088 m built in China is considered as an illustrative example. The reliability of the bridge is evaluated for the strength and serviceability performance functions. Results of the study show that when strength limit states for both girder and tower are considered, soil-pile interaction has significant effects on the reliability of steel cable-stayed bridges. Further, a detailed sensitivity study shows that the modulus of subgrade reaction is the most important soil-pile interaction-related parameter influencing the reliability of steel cable-stayed bridges.