• Korean small business review
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• v.41 no.2
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• pp.51-78
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• 2019

The purpose of this study is to classify unlisted companies' entering method into stock market and to find out a advantageous choice between IPO and SPAC. The research samples are two types(79 IPO companies and 46 SPAC companies) of 125 companies. Which were being listed in the KOSDAQ market from 2010 to 2017. The analysis results are as follows. At first, after analyzing the impact of well known variables such as asset size, company history and number of employees to select listing methods. I found that the variables of asset size and company history have a significant negative (-) effect on the SPAC variable. Secondly, the debt ratio variable has a significant positive (+) effect on the SPAC variable. Third, it was found that the ratio of profitability variables, such as operating income to sales have a systematically positive (+) effect on the SPAC variable. Fourth, I analyzed the impact of the largest stockholder in unlisted companies on the selection of listing methods. I found that the largest stockholder are systematically having a positive (+) effect on SPAC. The result means that unlisted companies that chose SPAC have the larger shareholder shares that are relatively higher than the unlisted companies that chose IPO.

• Journal of information and communication convergence engineering
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• v.1 no.3
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• pp.163-168
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• 2003

This paper presents a cascade multilevel PWM rectifier without the isolation transformers for energy build-up at each inverter modules. The features and advantages of the proposed PWM rectifier can be summarized as follows; I) It realizes the high power high voltage AC/DC power conversion, 2) It uses no transformer which is bulky and heavy, 3) It has hybrid structure so that switching devices can be effectively utilized, 4) It produces high quality AC current even in high power high voltage applications, 5) The input power factor remains unity by simple modulation index control. The multilevel rectifier is analyzed by using the circuit DQ transformation whereby the characteristics and control equations are obtained. Finally, it will be shown that the system simulation reveals the validity of analyses.

• Bulletin of the Korean Mathematical Society
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• v.30 no.2
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• pp.179-185
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• 1993

In this article S is a topologically complete subspace of $R^{1}$i.e., the relativized topology on S may be metrized so as to make S complete. B(S) is the Borel .sigma.-field of S. For .GAMMA. one takes a set of measurable monotone (increasing or dereasing) functions on S into itself. Make the assumption of pp. There exists $x_{0}$ and a positive integer $n_{0}$ such that (Fig.) It is then shown that there exists a unique inveriant probability to which $p^{(n)}$ (x,dy) converges exponentially fast in a metric (stronger than the Kolmogorov distance); this convergence is uniform for all x .mem. S. This generalizes an earlier result of Bhattacharya and Lee (1988) who considered monotone nondecreasing maps on S.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.64-70
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• 2015

This paper proposes fluorescent electronic ballast with high power factor and low line input current harmonics. The system performance can be improved by a charged pump circuit. Details of design and circuit operation are described. The proposed electronic ballast is modified from single-stage half bridge class D electronic ballast by adding capacitor parallel with each power switch and setting the circuit parameter to operate under class DE inverter condition. By using this proposed method the DC bus voltage can be reduced around by 50% compare with conventional class D inverter circuit. Because the power switches are operated at zero voltage switching condition and low dv/dt of class DE switching. The experimental results show that the proper frequency of the prototype is around 50 kHz with input power factor of 0.982, $THD_i$ 10.2% at full load and efficiency of more than 90%.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.10 no.2
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• pp.27-40
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• 2006

WiBro will speed up Ubiquitous era that will have positive effects in our economy such as increase in general production, consumer spending, general export, service qualify, and employment rate. Considering the fact that Wibro is currently commercialized in only few selected countries, Korea has advantage in standardizing technology, accumulating the related know-how, producing domestic parts, and technology marketing experience. I believe developing Wibro technology in Korea will deliver a significant amount of contribution to the future IT technology.

• Journal of Digital Convergence
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• v.7 no.2
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• pp.35-41
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• 2009

The information technology, in the digital economy era, does a very important role not only for the country's administrative management innovation but also for the business and for the everyday life. Specifically, the e-business for the company or organization is defined as "using the Internet and IT, rescheduling of business process management activities to increase productivity and efficiency and to create new business opportunities." Thanks to the Korea's recent efforts, overall level of informatization and digitalization is able to receive high praise. But the e-business readiness (e-readiness) level is still expected a lot of room for improvement. In this paper, I try to analyze the informatization level of Korea's by the EIU's e-business readiness index and IT industry competitiveness index, to prepare a full-scale e-business era of global competitiveness through any preparation that could do to improve the situation from the analysis of statistical data.

• Journal of Digital Convergence
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• v.7 no.2
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• pp.1-12
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• 2009

This study explored which the component factors on innovation brand to building an organizational culture of government. The innovation brand perception of organizational officers are in order brand awareness(recognition, discrimination) and brand loyalty(identification, ease of memory, meaning diffusion, the reaction of customer needs), brand salience, brand knowledge and brand innovation. The result of Importance-Performance analysis are as follows. We can see that Brand loyalty have Quadrant I meaning good management implementation. Brand Knowledge have Quadrant II meaning concentrate improving. Brand Uniqueness have Quadrant III meaning improving. And Recognition, familiarity and salience have Quadrant IV meaning low relative importance and high performance. The Quadrant IV consider the cost and benefit of brand management.

• Journal of computational fluids engineering
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• v.13 no.3
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• pp.51-61
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• 2008

The SMAC (Simplified Marker And Cell) algorithm is extended for an application to thermal non-equilibrium two-phase flows in light water nuclear reactors (LWRs). A two-fluid three-field model is adopted and a multi-dimensional unstructured grid is used for complicated geometries. The phase change and the time derivative terms appearing in the continuity equations are implemented implicitly in a pressure correction equation. The energy equations are decoupled from the momentum equations for faster convergence. The verification of the present numerical method was carried out against a set of test problems which includes the single and the two-phase flows. The results are also compared to those of the semi-implicit ICE method, where the energy equations are coupled with the momentum equation for pressure correction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.39-42
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• 1999

Adaptive array is using the array of antenna elements spatially and its output is the sum of each antenna elements output signal which is multiplied by the controlled weight coefficients corresponding to each elements. In this paper, for the BPSK and BFSK signals with S/I=2, S/N=10 is applied to the linear array antenna using the LMS & the Kalman filter algorithm. For the 4 elements equidistance linear array antenna system LMS and Kalman filter algorithm was used as the adaptive instruction principles and the application results to the constant amplitude envelope signals such as BPSK or BFSK can be seen that the computer simulation results are very fast in the convergence characteristics of directional patterns and the signal following characteristics.

• Bulletin of the Korean Mathematical Society
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• v.54 no.1
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• pp.343-358
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• 2017

Let {$X_i$} be a sequence of stationary ${\alpha}-mixing$ random variables with probability density function f(x). The recursive kernel estimators of f(x) are defined by $$\hat{f}_n(x)={\frac{1}{n\sqrt{b_n}}{\sum_{j=1}^{n}}b_j{^{-\frac{1}{2}}K(\frac{x-X_j}{b_j})\;and\;{\tilde{f}}_n(x)={\frac{1}{n}}{\sum_{j=1}^{n}}{\frac{1}{b_j}}K(\frac{x-X_j}{b_j})$$, where 0 < $b_n{\rightarrow}0$ is bandwith and K is some kernel function. Under appropriate conditions, we establish the Berry-Esseen bounds for these estimators of f(x), which show the convergence rates of asymptotic normality of the estimators.