• Structural Engineering and Mechanics
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• v.55 no.5
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• pp.1015-1035
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• 2015

A three-dimensional (3D) numerical analysis for the train-bridge interaction (TBI) system is actively developed in this study in order to investigate the vibration characteristics of rigid-frame reinforced concrete (RC) viaducts in both vertical and lateral directions respectively induced by running high-speed trains. An analytical model of the TBI system is established, in which the high-speed train is described by multi-DOFs vibration system and the rigid-frame RC viaduct is modeled with 3D beam elements. The simulated track irregularities are taken as system excitations. The numerical analytical algorithm is established based on the coupled vibration equations of the TBI system and verified through the detailed comparative study between the computation and testing. The vibration responses of the viaducts such as accelerations, displacements, reaction forces of pier bottoms as well as their amplitudes with train speeds are calculated in detail for both vertical and lateral directions, respectively. The frequency characteristics are further clarified through Fourier spectral analysis and 1/3 octave band spectral analysis. This study is intended to provide not only a simulation approach and evaluation tool for the train-induced vibrations upon the rigid-frame RC viaducts, but also instructive information on the vibration mitigation of the high-speed railway.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1832-1835
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• 2010

본 연구는 이상홍수와 급속한 도시화로 인하여 설계 및 축조 당시의 수문, 기상환경이 변화함에 따라 해마다 증가하는 저수지관련 홍수피해에 효율적으로 대처하기 위하여 국내 농업용 저수지 17,649개 중 14,154개(80.2%)에 해당하는 30만$m^3$ 이하의 소규모 저수지를 대상으로 댐 붕괴에 의한 저수지 하류의 피해 규모 및 피해양상을 정량화 할 수 있는 피해예측모델을 개발함으로써 저수지 하류하천 위험기준을 수립할 수 있는 방안을 제시하고자 한다. 이를 위해 경기도 용인시에 위치한 창리저수지(20.0만$m^3$)를 대상으로 댐 붕괴 시나리오를 작성하고 빈도별홍수량 및 가능최대홍수량(Probable Maximum Flood, PMF)을 산정하여 HEC-HMS 모형을 이용한 댐 붕괴 모의를 실시하였다. 하류부 홍수해석은 창리저수지 직하류 화곡천(1.12km) 구간에 대해 HEC-RAS 모형을 이용하여 댐 붕괴 홍수파 수문곡선에 따른 홍수범람도를 작성하였다. 또한 홍수범람구역에 해당되는 행정구역의 자산DB를 구축하고 홍수피해산정 방법으로 널리 사용된 다차원법(Multi - Dimensional Flood Damage Analysis, MD-FDA)과 기존 간편법의 장점을 살려 댐 붕괴에 따른 하류부 홍수피해액을 산정하였다.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.54-59
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• 2015

The performance of UV reactor which is used in water treatment is strongly affected by UV fluence rate and water flow in the UV reactor. Therefore, CFD tools are widely used in designing process of UV reactors. This paper describes the development of a computational fluid dynamics (CFD) methodology that can be used to calculate the performance of open channel type UV reactor used in wastewater treatment plant. All computations were performed using commercial CFD code, CFX, by considering three dimensional, steady, incompressible flow. The Eulerian-Eulerian multi-phase method were used to capture the water-air interface. The MSSS model, provided by UVCalc3D, was used to calculate the UV intensity field. The numerical predictions and calculated UV Dose were compared with experimental dataset to validate the CFD methodology. The reactor performance based on MS2 log reduction was well matched with measurements within 6%.

• Human Ecology Research
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• v.53 no.3
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• pp.293-307
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• 2015

Social commerce has a large impact on the emergence of the concept of society and individual lives that is recognized as one of the most important business areas in the Internet environment. A marketing agency, Trend Monitor (http://www.trendmonitor.co.kr), conducted a survey on social commerce usage and satisfaction level; subsequently, we used survey result data from 221 adult males and females for our research sample. Data analyses were conducted by reliability test, confirmatory factor analysis, t -test or one-way analysis of variance, and structural equation model (SEM) with IMB SPSS ver. 21.0 and ver. AMOS ver. 21.0. This study focused on multi-dimensional consumer innovativeness and found three elements of acceptability, competence, and distribution. Empirical verification through SEM presented data that suggests the three consumer innovativeness factors have a direct positive effect on social commerce that causes factors to indirectly affect satisfaction levels. This study indicated that the main consumption patterns in modern society take advantage of social commerce and satisfaction by improving a market economy to promote restoration. First, this study considers consumer innovativeness to have three factors. Secondly, research results help to understand relations between consumer innovativeness, use and satisfaction with social commerce that can help the social commerce industry establish effective market strategies through consumer innovativeness. The conclusion discusses implications for academic research and marketing strategies.

• Asia pacific journal of information systems
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• v.10 no.4
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• pp.1-20
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• 2000

Electronic Data Interchange(EDI) has the potential to improve business operations by expediting the exchange of business documents. It will also provide substantive operational and strategic benefits to the trading firms. However, the successful implementation of EDI systems requires the mutual trust and cooperation between the trading firms. The extent of EDI diffusion and performance depends on inter-organizational, intra-organizational, as well as innovation factors. Researches based on the sociopolitical process framework in the use of IT, organizational theory, resource dependence theory, and innovation diffusion theory have identified 3 inter-organizational variables(transaction climate, dependence, external IS expert support) and 4 intra-organizational variables(strategic IS planning, infrastructure, top management support, education/training,), and 3 innovation variables(compatibility, relative advantage, cost) that affect EDI diffusion. In this study, a multi-dimensional measure on EDI diffusion has been developed to capture the external and internal integration. Then, the influence of these 10 variables on the extent to which the EDI adopting firms pursue diffusion has been examined. Whether more diffusion leads to superior performance has also been studied. International trade managers from 107 firms in the trade industry participated in a field survey. The results based on a structural equation model(SEM), developed using AMOS, provide quite a strong support for the hypothesized relations. Both education/training and IT infrastructure influenced external and internal diffusion of EDI systems. Internal diffusion of EDI enables the adopting firms to improve operational and strategic performance, whereas external diffusion contributes only to operational performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.659-665
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• 2008

The 1-D numerical study of the interior ballistics has been conducted. The unsteady compressible 1-D CFD code using SIMPLER algorithm and QUICK scheme has been developed. The mathematical model of the two-phase flow has been established for the behavior of the interior ballistics. The moving boundary due to the projectile motion as the physical phenomena of the interior ballistics results in the varied control volume. In order to analyze the moving boundary, the numerical codes, which apply the ghost-cell extrapolation method and the Lagrangian method respectively, have been developed. The ghost-cell extrapolation method has been used in the Eulerian coordinate system. The Lagrangian method has been used in Non-Eulerian coordinate system. These codes have been verified through the analysis of the free piston motion problem in the tube. Through this study, the basic techniques of the numerical code for the multi-dimensional two-phase flow of the interior ballistics have been obtained.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.4
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• pp.100-106
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• 2006

We analyze a voice/data integrated traffic model of the cellular mobile communication system with hybrid guard channels for voice and handoff calls. In a multi-service integrated wireless environment, quality of service guarantee is crucial for smooth transportation of real time information. Real time voice traffic requires a guaranteed upper bounded on both delay and packet error rate, whereas data traffic does not. Voice traffic has high transmission priority over data packets. Thus one of the important problems is the design of admission control schemes which can efficiently accommodate the differential quality of service requirements. In this paper, a hybrid guard channel scheme is considered in which arriving calls are assigned channels as long as the number of busy channels in the cell is below a predetermined first threshold. When the number of busy channels reaches the first threshold, new originating data calls are queued in the infinite data buffer. Then reaches second threshold, only handoff calls are assigned the remaining channels and new originating voice calls are blocked. We evaluate the system by a two-dimensional Markov chain approach and generating function method and obtain performance measures included blocking probability and forced termination probability.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.225-230
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• 2009

From the view point of railway vehicle dynamics, the interaction between wheel and rail have an huge effect on the behavior of the vehicle. This phenomenon is an unique motion, only for railway vehicles. Furthermore, close investigation of the backgrounds of the interaction is the key to estimate the dynamic behavior of the vehicle, successfully. To evaluate the model including flexible bodies such as car body and catenary system of the next generation express train, it is necessary to develop proper dynamic solver including a wheel rail contact module. In this study, wheel-rail contact module is developed using the general purpose dynamic solver. First of all, the procedure for calculation of the wheel-rail contact force has been established. Generally, yaw angle of the wheelset is ignored. Sets of information are summarized as tables and splined for further uses. With this information, normal force and creep coefficient can be extracted and used for FASTSIM algorithm, which has been shown good reliability over years. Normal force and longitudinal, lateral force at the contact surface are also calculated. Those data are verified by commercial railway simulation program 'VAMPIRE'. This procedure and program can offer a basic process for estimation of the dynamic behavior and wear of the wheel-rail system, even while running on the curved rail. Finally, multi-dimensional inspection tool will be developed including the prediction of the derailment.

• International Journal of Computer Science & Network Security
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• v.21 no.12spc
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• pp.556-564
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• 2021

Numerous spatial and transform-domain-based conventional denoising algorithms struggle to keep critical and minute structural features of the image, especially at high noise levels. Although neural network approaches are effective, they are not always reliable since they demand a large quantity of training data, are computationally complicated, and take a long time to construct the model. A new framework of enhanced hybrid filtering is developed for denoising color images tainted by additive white Gaussian Noise with the goal of reducing algorithmic complexity and improving performance. In the first stage of the proposed approach, the noisy image is refined using a high-dimensional non-local means filter based on Principal Component Analysis, followed by the extraction of the method noise. The wavelet transform and SURE Shrink techniques are used to further culture this method noise. The final denoised image is created by combining the results of these two steps. Experiments were carried out on a set of standard color images corrupted by Gaussian noise with multiple standard deviations. Comparative analysis of empirical outcome indicates that the proposed method outperforms leading-edge denoising strategies in terms of consistency and performance while maintaining the visual quality. This algorithm ensures homogeneous noise reduction, which is almost independent of noise variations. The power of both the spatial and transform domains is harnessed in this multi realm consolidation technique. Rather than processing individual colors, it works directly on the multispectral image. Uses minimal resources and produces superior quality output in the optimal execution time.

• Journal of Information Technology Applications and Management
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• v.25 no.4
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• pp.123-143
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• 2018

The domestic multiplex industry provides consumers with a choice of movies and a variety of contents and entertainment facilities and services. In addition, the number of movie theaters with the significant market potential is also steadily increasing in the competitive multiplex market environment. For the analysis, we conducted research on 300 adolescents who have experienced using domestic multiplex mobile service within the recent year. This study examined the structural relationship among the multi-dimensional mobile service quality of multiple, enjoyment of use, and online word of mouth intention. Also, it explored the mediating effect of enjoyment of use and the moderating effect of gender in the structural model. As a result, the mobile service quality of multiplex has a significant effect on the online word of mouth intention through the enjoyment of use. However, there was no moderating effect of gender of participating adolescents in the relationships. Based on the analysis of empirical results, this study discussed a series of theocratical and practical implications for the marketing strategies of multiplex in the highly competitive market.