• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.212-224
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• 1998

There are two major factors of degrading the performance in the forward link of DS/CDMA systems. One is the multiple access interference (MAI) caused by using the same frequency bands simultaneously and the other is the multipath lading due to multipath propagation. PN codes which have minimum cross correlation properties among spread spectrum codes are necessary to reduce the MAI. In the conventional IS-95A system, the PN sequence has the period of $2^{15}$ and is of the length of 64 chips for spreading each data. In this case, since the length of PN code per bit is very short compared to the period of the PN code, the performance of the conventional system is not satisfied in view of suppressing the multipath interference. However, the correlation property of the PN codes at the demodulation can be improved by increasing the interval of Integration at the demodulation. This paper proposes a demodulation method to reduce the cross correlation among PN codes. The performance of the proposed demodulation method is investigated through computer simulations. We used multipath Ray lading channel and AWGN channel in the simulation. Our simulation results show the improved performance of $0.25{\sim}0.5dB$ SNR in a given BER compared to the conventional demodulation scheme.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.312-316
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• 2000

A study has been made to investigate the effects of hot isostatic pressing(HIP ping) on bond strength and elevated temperature characteristics of thermal barrier coating(TBC). The specimens were prepared by HIPping of TBC which is composed of the ceramic top coat(8wt%$Y_2$$O_3$-$ZrO_2$) and the metallic bond coat on the matrix of IN738LC superalloy. The results showed that the porosity and microcracks in the ceramic top coat of TBC were significantly decreased by HIP. As a result, the bond strength of the HIPped coating was increased above 48% compared to that of as-coated specimen and microstructure was homogenized. It was found that the thermal cycle resistance of HIPped coating was inferior to that of as-coated specimen. It was considered that this result was mainly caused by the reduction of internal defects in the top coat layer which could play a role in relaxing the thermal stress due to a large difference in thermal expansion between TBC and matrix.

• Journal of Digital Contents Society
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• v.19 no.6
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• pp.1043-1050
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• 2018

As the cconvenience economy of food culture becomes more widespread and the consumption trends for easy and convenient meals grew, every food company is making their various efforts to provide better service. Along with this change, various methods have been allowed for quick and easy ordering. Especially, the introduction of kiosk systems with various merits such as reduction of queues for cashes, saving labor costs, and smoothness of business processes have been actively growing recently. If kiosk system provides not only order but also systematic contents and interface design considering differentiated identity from other companies, brand image enhancement and customer service strategy would be available as well. A kiosk GUI design for effective interactions that provides more usability and satisfaction to users by analyzing the structure and contents of kiosks in fast food stores and GUI designs and investigating usage patterns and design preferences of kiosks through user surveys.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.21-28
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• 2000

Refractory metals, W and Ti, and their nitrides, $W_2N$ and TiN, were investigated for using as an ohmic contact material with SiC single crystalline thin films. The possibility of nitride materials for using as a stable ohmic contact material of SiC at high temperatures was examined by considering the thermal stability depending on the heat treatment temperature, their electrical properties and protective behavior from the interdiffusion. W contact with SiC thin films, deposited by using new organosilicon precursor, bis-trimethylsilylmethane, showed the lowest resistivity, $2.17{\times}10^{-5}$Ω$\textrm{cm}^2$. On the other hand, Ti-based contact materials showed higher contact resistivity than W-based ones. The oxidation of contact materials was restricted by applying Pt thin films on those electrodes. Nitride electrodes had rather stable electrical properties and better protective behavior from interdiffusion than metal electrodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4A
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• pp.302-308
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• 2009

In this paper, two receive diversity combining techniques are proposed for single-carrier Sequency division multiple access (SC-FDMA)-based cooperative relay systems when DFT spreading sizes for mobile station (MS) and relay station (RS) are different. A simplified-MRC (5-MRC) technique performs diversity combining in the time domain using the estimated channel weight and initial values obtained by SC-FDMA signal detection. An interference rejection-MRC (IR-MRC) technique performs diversity combining in the frequency domain by adjusting DFT spreading size in the receiver. It is shown by computer simulation that the proposed receive diversity combining techniques achieve a significant performance gain over the conventional MRC technique with zero forcing (ZF) detector.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.1
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• pp.28-36
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• 1996

The influence of vertical eddy viscosity to the nonlinear interaction of tidal current and wind-induced current is examined using a point model. A zero-equation turbulence model is derived by simplifying the q$^2$-q$^2$1 turbulence model under the assumption that the generation of turbulence kinetic energy is balanced with its dissipation and is further modified to include the depth of frictional influence properly The zero-equation turbulence model is derived and the possibility of resonance in the presence of Coriolis effect is suggested. The amplitudes of tidal currents remain the same regardless of the applied wind stress, but the over-tide component is generated due to the nonlinear interaction of tidal current and wind-induced current. Significant changes in the vertical profile of wind-induced currents can occur according to tide-induced background turbulence. The turbulence model can give rise to misleading results when applied to the wind-driven circulation in the tide-dominated sea such as Yellow Sea unless the tide-induced background turbulence is adequately included in the parameterization of vertical eddy viscosity.

• Journal of The Korean Association For Science Education
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• v.32 no.4
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• pp.671-685
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• 2012

In this study, we developed an analogical experimental design strategy emphasizing understanding and checking stages and applied it to four groups consisting of 7th grade science-gifted students. We classified the patterns of experimental design processes and analyzed the verbal interactions among the science-gifted students at the levels of turn and interaction unit. The analyses of the results reveled that three groups were relevant to reinitiated motion and the other to backward-divergent motion. In the analyses of turn and interaction unit, the frequencies of the statements related to the task were high, especially 'making suggestion' and 'elaborated symmetrical interaction'. The analyses for each stage of strategy indicated that the frequencies of 'explain', 'question', and 'cumulative interaction' at understanding stage were high. At designing stage, the frequencies of 'making suggestion', 'cumulative interaction', and 'disputative interaction' were found to be high. At checking stage, 'making suggestion', 'receiving opinion', and 'disputative interaction' were high. In the comparison of the patterns, the qualitative differences among interaction unit were found at all the stages, whereas there were differences only between designing and checking stages in the turn cases. Educational implications of these findings are discussed.

• Information Systems Review
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• v.10 no.3
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• pp.257-287
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• 2008

Grounded in the prior literatures on acceptance and diffusion of IT and innovation in the level of organization research, 3 major constructional factors such as Motivation, IT resistance, and IT change management were investigated to suggest propositions from 15 multi-cases of PLM from 6 different companies in Automotive OEMs and suppliers, and we posited that the diffusion is continued only when motivation is stronger enough to overcome IT resistance as a fundamental finding and basis of this research on PLM acceptance and diffusion. The Motivation was found to be initiated and categorized from three different factors such as environmental factors, organizational factors, and technological factors, providing key propositions for further research: (1)The Automotive suppliers, contrary to OEM, are affected more by the demand of inter-connectivity as an environmental factor, while the other factors are similarly influencing to them, (2)The big organizations are influenced more by the champion, while the small organizations get influenced more by leader. (3)When the trend, inter-connectivity and complexity get stronger, the motivation gets more strongly influenced by the perceived benefit in the technological context. Regarding Change management we suggests IT change management is supportive to overcome IT resistance and also to enforce Motivation, and the critical mass exists differently according to the market maturity adopted, and more market matured technology has lower critical mass, implies less requirement of IT change management than less market matured technology.

• Journal of the Korean Society of Groundwater Environment
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• v.1 no.2
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• pp.105-112
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• 1994

To investigate the migration behavior of contaminants in rocks. adsorption and diffusion experiments for Sr as a sorbing contaminant and for Cr-EDTA as a non-sorbing contaminant were carried out on granitic rocks. The Sr adsorption on separated minerals and crushed rocks tends to slightly increase with increasing pH. It also greatly decreases with the increase of ionic strength in NaCl solution. Among separated minerals, biotite and sericite have adsorbed much more amount of Sr than other rock-forming minerals, such as quartz, plagioclase, and potassic feldspar, because the specific surfaces and cation exchange capacities of phyllosilicates are generally much greater than those of the other rock-forming minerals. The intrinsic diffusion coefficients of Cr-EBTA for granitic rocks differ little from those of Sr. This indicates that they are independent of water-rock interactions. Experimental data show that the intrinsic diffusion coefficients are positively correlated with the porosities of the rocks. They are close to the theoretically predicted values, especially in pre-steady state diffusion region, with the increase of rock sample thickness.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.10 no.1
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• pp.143-151
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• 2015

Technology convergence, recently accelerated in various technical fields, can be achieved by discovering a new technology while exchanging the knowledge among the different technologies and utilizing such knowledge into the existing fields of technology. In particular, technology convergence actively occurs in knowledge-intensive ICT. However, limited research is available on the routes of ICT technical knowledge diffusion because of insufficient data. Therefore, this study built a database on the citations of patent data applied from 2006 to 2013 in Korea and their cited patents. We drew a patent citation network, a technology citation network and an applicant citation network, after which we analyzed the routes of technical knowledge diffusion. Results showed that ICT played a leading role in knowledge citation among technologies and that such diffusion took a shorter time in technology citation when it occurred more frequently and when the citation occurred between ICTs. In addition, most of the ICT showed a strong citation relationship with the other ICTs or such technologies in the field of physics or electricity, whereas electric elements (H01) showed various citation relationships with technologies other than ICT. Furthermore, we found a strong technology diffusion relationship between domestic corporations and domestic natural persons. National organizations often cited the patents of other applicants, whereas the patents of domestic corporations were actively cited between domestic corporations or by other applicants. Thus, this study is expected to be useful in measuring the performance of technologies, including the diffusion to other technologies. As well as in considering the routes of technical knowledge diffusion in Korea.