Park Y.,Hankuk University of foreign Studies |
Yoon H.,Hyupsung University
Journal of Electromagnetic Engineering and Science | Year: 2017
In this paper, a systematic and statistical calibration technique was implemented to calibrate a high-speed signal converting system containing multiple digital-to-analog converters (DACs). The systematic error (especially the imbalance between DACs) in the current combining network of the multi-DAC system was modeled and corrected by calculating the path coefficients for individual DACs with wideband reference signals. Furthermore, by applying a Kalman filter to suppress noise from quantization and clock jitter, accurate coefficients with minimum noise were identified. For correcting an arbitrary waveform generator with two DACs, a co-simulation platform was implemented to estimate the system degradation and its corrected performance. Simulation results showed that after correction with 4.8 Gbps QAM signal, the signal-to-noise-ratio improved by approximately 4.5 dB and the error-vector-magnitude improved from 4.1% to 1.12% over 0.96 GHz bandwidth. © Copyright The Korean Institute of Electromagnetic Engineering and Science. All Rights Reserved.
Park Y.,Hankuk University of foreign Studies |
Yoon H.,Hyupsung University
Measurement: Journal of the International Measurement Confederation | Year: 2017
This paper presents a frequency interleaving method to correct non-ideal characteristics of wideband signal generators. By effectively segmenting a discrete Fourier transform dataset into frequency-interleaving blocks, the proposed method is computationally more efficient than the conventional method based on Fast Fourier Transform (FFT). In cases the quality of frequency analysis can be improved by zero padding such as characterizing impulse responses, this method is effective because it is possible to interleave two or more FFT results to achieve better frequency resolution. To verify the proposed method, an arbitrary signal generator was tested with a 64 quadrature-amplitude-modulation waveform. Compared with the original signal quality, the proposed method improves the in-band signal-to-noise ratio by 9 dB, and the error-vector magnitude decreases from 2.1%rms to 0.78%rms. In all cases, the computation speed was faster than that of conventional FFT. © 2017 Elsevier Ltd
Kim J.U.,Sungkyunkwan University |
Kim W.J.,Hyupsung University |
Park S.C.,Sogang University
Computers in Human Behavior | Year: 2010
The principal objective of this study was to investigate the mediating and moderating effects of product involvement and trust toward websites in relation to the effects of the attributes of web advertisements on customers' purchase intentions. We collected data consisting of a total of 264 responses from individuals with previous experience with purchasing products from online shopping mall sites, and utilized the PLS (partial least squares) method to analyze the collected data. Our findings demonstrated that consumers with greater product involvement tended to shop in shopping malls, where they could obtain more information on products, and that consumers with low product involvement tended to be more willing to consider entertainment. Additionally, consumers with higher levels of trust toward websites tended to be influenced by perceived entertainment and thus stay longer at shopping sites; conversely, consumers with low levels of trust toward websites tended to be more willing to consider perceived informativeness as minimizing environmental uncertainty. On the basis of our results, online shopping malls must stress the intrinsic attributes of products to attract highly-involved consumers and must present a benevolent corporate image for consumers concerned with better service. Our results also demonstrated that, for less-involved consumers who wish to search for products to present, it may be appropriate to mix entertainment components with product information, and also to implement creative web interface designs for more effective browsing. © 2010 Elsevier Ltd. All rights reserved.
Bhattacherjee A.,University of South Florida |
Bhattacherjee A.,Sogang University |
Park S.C.,Hyupsung University
European Journal of Information Systems | Year: 2014
This study presents and empirically validates a model of end-user migration from client-hosted computing to cloud computing. Synthesizing key findings from IT adoption and post-adoption research, switching research, and cloud computing studies, it builds an integrative framework of cloud migration using migration theory as a theoretical lens, and postulates interdependencies among these predictors. A longitudinal survey of Google Apps adoption among student subjects in South Korea validates our proposed model. This study contributes to our nascent body of knowledge on IT migration by drawing attention to this emerging phenomenon, demonstrating how migration research is different from IT adoption research, identifying salient factors that enable or hinder cloud migration, elaborating interdependencies between these different predictors, and bringing in migration theory as a referent theory to the information systems literature. © 2014 Operational Research Society Ltd. All rights reserved.
Hwang Z.,Hyupsung University |
Lee J.H.,Korea University |
Kang J.W.,Korea National University of Transportation
Journal of Computational and Theoretical Nanoscience | Year: 2013
We present the simple schematics of the double-gate graphene-nanoribbon (GNR)-based nanoelectromechanical relay and the model schematic of its fabrication processes, and investigated their operation dynamics via classical molecular dynamics simulations. The key operations of the proposed GNR relay are based on the low mass density, the large area, and the flexible deflection of the GNR. The electromechanical dynamics of the GNR-relay are well understood by five forces such as the capacitive force between the top electrode and the GNR, the van der Waals force between the top electrode and the GNR, the capacitive force between the bottom electrode and the GNR, the van der Waals force between the bottom electrode and the GNR, and the elastic force of the GNR. The switching speed of the GNR-relay decreases by increasing the electrostatic force. We anticipate the realization of this proposed GNR-based nano-electromechanical rely in further experimental works. Copyright © 2013 American Scientific Publishers. All rights reserved.
Seo W.,Hyupsung University |
von Rabenau B.,Ohio State University
Journal of Urban Planning and Development | Year: 2011
Although a large number of studies have examined the impact of housing and neighborhood characteristics on housing prices, they have not systematically considered the impact of physical conditions of the immediate neighborhood on housing prices, specifically conditions associated with physical disorder. Most likely, this failure has occurred because such data do not exist in published form. The main purpose of this study is to focus on the impact of physical disorder at the microneighborhood level on property resale values by using a hedonic-price-model approach. The results highlight the costs that neighbors may inflict on one another by not maintaining their houses and neighborhood. For the first time, the results provide specific estimates of the cost associated with individual physical-disorder attributes. The results are also indicative of the importance externalities play in neighborhood change and the need for policy intervention in preventing neighborhood decline. © 2011 American Society of Civil Engineers.
Wu M.,Tongji University |
Wu Y.,Tongji University |
Kim J.-Y.,Hyupsung University
Thin-Walled Structures | Year: 2011
The traditional Ethylene Tetra Fluoro Ethylene (ETFE) foil cushion is in the form of air cushion, whose structural stiffness is offered by the inner air pressure. Because the air supply and control systems are needed, air cushion structures cost extra energy and need much maintenance. In order to overcome the shortcomings of air cushion, the ETFE foil spring cushion that uses a spring to take the place of air pressure is developed in this paper. At first, the analytical method for shape finding analysis and stress analysis of the spring cushion is described in the paper. A numerical example is shown by means of the software package ANSYS and the suggested method so as to verify the validity of the method. Then, a model experiment on the ETFE foil spring cushion is carried out. In the loading test, the compression of spring is recorded and the experimental results are compared with the analytical results. At the end of the paper, an experimental hall using both ETFE foil air cushion units and spring cushion units as its roof structure is introduced. Through the construction and daily use of the experimental hall, the spring cushion system shows advantages such as easier construction, needing no air supply and control equipments, no running energy and little maintenance compared with the air cushion system. © 2011 Elsevier Ltd. All rights reserved.
Kim C.-S.,Hyupsung University |
Chung S.-J.,Hyupsung University
Building and Environment | Year: 2011
Museums have the most complicated lighting criteria of common building types. A stable lighting environment for visitors and artworks should be guaranteed within the exhibition areas of museums. This paper presents a challenge to the application of daylighting simulation integrated into the architectural design process (DSADP). The scale model measurements and computer simulations were carried out to verify the computer program RADIANCE. A comparison between the measurement and simulation results showed that there was considerable relative error at measurement points. Therefore, a correction factor (CF) and corrected simulation (CS) were recalculated to correct the simulation results. The Seoul Museum of Art (SMOA) was selected to make an application of DSADP. The monitor and sawtooth-shaped toplights were chosen as attractive alternatives for the existing skylight of SMOA. The application of DSADP was carried out by changing the light transmission efficiency and opening size of the toplights. The RADIANCE results showed that computer simulation models can accurately represent the lighting environment under clear sky conditions, and more importantly, they can be used to propose an alternative toplight for SMOA. Therefore, the research results showed that DSADP technology would be very useful during the schematic design stage of the architectural design process. The findings of this research also suggested that there are large differences between the real sky conditions for scale model measurements and the CIE sky conditions for computer simulations. More studies are required to reduce the differences between real and simulated sky conditions. © 2010 Elsevier Ltd.
Ko Y.H.,Hyupsung University
International Journal of Software Engineering and its Applications | Year: 2014
In these days, the importance of money is increased. The wise investors want to have an useful tool which provides overall information in Option market. The KOWA system is the useful tool to provide this overall information. It is Ko's Option Windows Agent that provides overall information from fragmentary data exported by HTS. Conventionally Option Greeks are used for position traders. But they have used the fragmentary Greeks such as delta, gamma, theta, etc. This paper suggests the new parameters extracted by overall view. Those are omega, mu and sigma. It can be extracted by KOWA system on real time. And the methods to compute the new Greeks are also inspected. The examples are appended which are based on real data of Korean Option market. These new Greeks might be very useful to the wise investors. And KOWA system might be a very useful tool. © 2014 SERSC.
Yoon H.,Hyupsung University |
Choi B.,Ewha Womans University
International Journal of Software Engineering and Knowledge Engineering | Year: 2011
We propose a test case prioritization strategy for risk based testing, in which the risk exposure is employed as the key criterion of evaluation. Existing approaches to risk based testing typically employ risk exposure values as assessed by the tester. In contrast, we employ exposure values that have been determined by experts during the risk assessment stage of the risk management process. If a given method produces greater accuracy in fault detection, that approach is considered more valuable for software testing. We demonstrate the value of our proposed risk based testing method in this sense through its application. © 2011 World Scientific Publishing Company.