• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.7
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• pp.581-588
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• 2013

In the basic GMSK, the modulated signals are generated by the preprocessing of NRZ pulse trains with the gaussian low pass filter. In this paper, we proposed the GMSK modulation system with the delta pulse trains. The proposed system constructed with the gaussian pulse generator triggered by the bipolar delta pulse, the differentiator between $+T_b/2$ and $-T_b/2$, and then a matched filter for frequency-modulation function. The spectrum of proposed system was found to be smaller than about 35[%] at 40[dB] attenuated bandwidth, and the center spectrum to be lower than the basic GMSK with zero-crossing property.

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.71-80
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• 2013

Fire-resistant (FR) test data for a square concrete-filled steel tube (CFT) columns consisting of high-strength steel (fy>650MPa) and high strength concrete (fck>100MPa) under axial loads are insufficient. The FR behavior of square high-strength CFT members was investigated experimentally for two specimens having ${\Box}-400{\times}400{\times}15{\times}3,000mm$ with two axial load cases (5,000kN and 2,500kN). The results show that the FR performance of the high-strength CFT was rapidly decreased at earlier time (much earlier at high axial load) than expected due to high strength concrete spalling and cracks. In addition, a fiber element analysis (FEA) model was proposed and used to simulate the fiber behaviour of the columns. For steel and concrete, the mechanical and thermal properties recommended in EN 1994-1-2 are adopted. Test results were compared to those of numerical analyses considering a combination of temperature and axial compression. The numerical model can reasonably predict the time-axial deformation relationship.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.300-306
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• 2012

In this paper, we propose a vision based hand motion recognition method for an untouchable user interface of smart devices. First, an original color image is converted into a gray scaled image and its spacial resolution is reduced, taking the small memory and low computational power of smart devices into consideration. For robust recognition of hand motions through separation of horizontal and vertical motions, the horizontal principal area (HPA) and the vertical principal area (VPA) are defined respectively. From the difference images of the consecutively obtained images, the center of gravity (CoG) of the significantly changed pixels caused by hand motions is obtained, and the direction of hand motion is detected by defining the least mean squared line for the CoG in time. For verifying the feasibility of the proposed method, the experiments are carried out with a vision system.

• Geotechnical Engineering
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• v.1 no.1
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• pp.5-12
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• 1985

Ocassionally it is used for simple extensions of Terzahgi's theory to account for time-depend- tint loading but there is little evidence of application in more complicated consolidation theories that take into account such effects as nonlinear stress.strain, layered systems or large strains. The purpose of this paper provides an efficient computer algorthm based on numerical analysis using finite difference method which account for multi-layered soils to determine the degree of consolidation and excess pore pressures relative to time and positions more realistically. The explicitly scheme of solving the consolidation equations has been investigated from the point of view of the stability conditions and the convergence with variance of the operator as well as to obtain an optimal divided depth ratios of total depth. A comparison of the settlement predictions with both the classical analysis and the algorithm based on numerical analysis indicates that the new algorithm scheme is found to be superior to the classical theory in the layered soils.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.7
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• pp.26-36
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• 2002

Mach-Zehnder type traveling-wave optical modulators with 3-section and 5-section phase reversal were designed and fabricated on z-cut $LiNbO_3$ substrates. Optical waveguides were designed by means of the FDM(Finite Difference Method). Design of CPW traveling-wave electrodes were performed by the SOR(Successive Over Relaxation) in the active region and by the CMM(Conformal Mapping) in the input/output section. The optical response R(${\omega}$ calculated based on the measured S-parameters showed the bandwidth of 15GHz centered at 25GHz for the 3-section, and the bandwidth of 22GHz at 45GHz for the 5-section.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.11
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• pp.43-49
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• 2000

In this paper, we have modeled and fabricated $1{\times}5$ equal power splitter for 1.55${\mu}m$ wavelength using finite-difference beam propagation method and $Ag^+-Na^+$ ion-exchanged method in BK7 glass, respectively. The power splitting ratio could be controlled by changing the center waveguide gap and the inner Y-branch angle. As a result, the power splitting ratio shows 0.46dB when the waveguide width, the inner Y-branch angle and the center waveguide gap are 4.5${\mu}m$, 0.3 degree and 575${\mu}m$, respectively.

• Journal of Digital Convergence
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• v.19 no.9
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• pp.9-18
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• 2021

Constructing the Metropolitan Railway Express (the GTX) may have an impact on consumer confidence and housing sales price located near the planned route. This study looked at how consumers' psychology and housing prices change as the large-scale transport infrastructure plane was planned. Also, it looked at the relationship between consumer sentiment and housing prices to analyze the impact of new transportation facilities inflows. Using a correlation analysis, the relationship between the consumer sentiment index and the actual transaction price of apartments was identified. The impact of GTX on the consumer sentiment index and the actual transaction price of apartments was looked at using the Difference-in-Differences methodology. Our finding shows that the construction plan of a large-scale transportation infrastructure in the metropolitan area affects the sentiment of housing consumption and actual transactions. In a situation where the government is speeding up the construction of a wide-area transportation network such as GTX with the goal of becoming a city where people can commute to downtown Seoul within 30 minutes, policies that can stabilize the housing market in transportation hubs should be suggested.

• (The)Korea Educational Review
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• v.24 no.3
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• pp.167-189
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• 2018

Using the 1st to 5th wave data from Gyeonggi Education Panel Study(GEPS), this study analyzed the change of school effectiveness of middle schools by innovation school expansion in Gyeonggi province. For this purpose, the analysis employed difference-in-difference model with repeated cross-sectional data and the dependent variable was comprised of academic achievement, school satisfaction, creativity, and sense of community. Results showed that the effectiveness of innovation schools had not significantly different from general schools before innovation school expansion but significantly improved in academic achievement and school satisfaction compared to general schools after the policy applied. On the other hand, the school effectiveness in creativity and sense of community not significantly different between innovation and general schools in both before and after. As time passes, the effectiveness of existing innovation schools in the academic achievement was improved and the school satisfaction was maintained. In addition, the effectiveness in satisfaction of the schools was improved as general schools with high effectiveness in academic achievement were transformed into innovation schools. Based on the results, the policy for innovation school expansion was evaluated and the issues related to this policy were discussed.

• 지역과문화
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• v.7 no.4
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• pp.21-48
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• 2020

The purpose of this study is to analyze how the integrated heritage conservation actually affected the urban economy of historical cities. To this end, this study examined the trends and meanings of an integrated heritage conservation, and a relationship between sustainable urban development and integrated heritage conservation to find out connectivity with urban economy. Before an empirical analysis of domestic policy of integrated conservation of heritage, this study overlooked the system of the preservation and promotion of ancient cities, which can be called integrated heritage conservation system in Korea, and examined how the historic landscape improving project, which is being implemented as part of the policy of the preservation and promotion of ancient cities, actually affected the urban economy. This study empirically identified the impact of the project through a land price analysis of the region. This study focused on analyzing an impact of the project on a price of land in the proximity of subsidized land lot and analyzed the impact through Difference-In-Difference method. In particular, the project effect was analyzed only for the settlement zones among the preservation and promotion zones where the project was carried out, and as a result, it was confirmed that the average price of lands in the proximity of subsidized land increased more over the same period than in the areas where the project was not intensively implemented.

• Korean small business review
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• v.41 no.2
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• pp.25-50
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• 2019

Although Korean government has implemented size-dependent policy, so called "the designation of SMEs-suitable industry", promoting SMEs growth, our understanding in the effectiveness of the policy is limited. We investigate the effect of the policy on SMEs performance in food product and beverages industry, which accounts for the majority in the SMEs-suitable industry. From the perspective of sales, profitability, and R&D intensity, which is regarded as indigenous effort for growth, we find the heterogeneity in the effectiveness of the policy across the sub-sectors in the industry. However, overall the policy does not significantly contribute to the growth of sales, profitability, and facilitation of R&D activity for indigenous innovative efforts of SMEs. Our study advances the theoretical discussion on the effect of the policy with the disaggregated level of analysis, i.e, sub-sector level. Our findings also contribute to the resolution of social and political conflicts between pros and cons of the policy. Our study suggests that policy makers should develop more sophisticated policy that incorporate the specific characteristics of individual sub-sectors. They also need to invest more resources in enhancing the effectiveness of the policy and accelerating SMEs innovative efforts.