• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.1-16
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• 2022

Social network service (SNS) using mobile or web is growing rapidly, and the emergence of various platform services is causing innovative changes in social network service (SNS). This study is to identify the target relation factors of social network users and to empirically study the causal relationship of how much these factors affect user satisfaction through pleasure and self-efficacy. To present an effective and efficient development plan in. In order to empirically verify the research model of this study, a survey was conducted with the general public who had experience using social network services (SNS). Path analysis was performed. As a result, it was possible to verify the correlation of the object relational factors on user satisfaction through pleasure and self-efficacy.First, non-excluded had a significant effect on pleasure, but did not significantly affect self-efficacy. Second, stability attachment did not significantly affect both enjoyment and self-efficacy. Third, social ability did not significantly affect both enjoyment and self-efficacy. Fourth, self-centeredness did not have a significant effect on both enjoyment and self-efficacy. Fifth, pleasure had a significant effect on both self-efficacy and user satisfaction. Sixth, self-efficacy had a significant effect on user satisfaction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2B
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• pp.187-197
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• 2008

This study is to assess the impact of future land use change on hydrology and water quality in Gyungan-cheon watershed ($255.44km^2$) using SWAT (Soil and Water Assessment Tool) model. Using the 5 past Landsat TM (1987, 1991, 1996, 2004) and $ETM^+$ (2001) satellite images, time series of land use map were prepared, and the future land uses (2030, 2060, 2090) were predicted using CA-Markov technique. The 4 years streamflow and water quality data (SS, T-N, T-P) and DEM (Digital Elevation Model), stream network, and soil information (1:25,000) were prepared. The model was calibrated for 2 years (1999 and 2000), and verified for 2 years (2001 and 2002) with averaged Nash and Sutcliffe model efficiency of 0.59 for streamflow and determination coefficient of 0.88, 0.72, 0.68 for Sediment, T-N (Total Nitrogen), T-P (Total Phosphorous) respectively. The 2030, 2060 and 2090 future prediction based on 2004 values showed that the total runoff increased 1.4%, 2.0% and 2.7% for 0.6, 0.8 and 1.1 increase of watershed averaged CN value. For the future Sediment, T-N and T-P based on 2004 values, 51.4%, 5.0% and 11.7% increase in 2030, 70.5%, 8.5% and 16.7% increase in 2060, and 74.9%, 10.9% and 19.9% increase in 2090.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2B
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• pp.215-224
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• 2008

The effect of streamflow considering future land use change and vegetation index information by climate change scenario was assessed using SLURP (Semi-distributed Land-Use Runoff Process) model. The model was calibrated and verified using 4 years (1999-2002) daily observed streamflow data for the upstream watershed ($260.4km^2$) of Gyeongan water level gauging station. By applying CA-Markov technique, the future land uses (2030, 2060, 2090) were predicted after test the comparison of 2004 Landsat land use and 2004 CA-Markov land use by 1996 and 2000 land use data. The future land use showed a tendency that the forest and paddy decreased while urban, grassland and bareground increased. The future vegetation indices (2030, 2060, 2090) were estimated by the equation of linear regression between monthly NDVI of NOAA AVHRR images and monthly mean temperature of 5 years (1998-2002). Using CCCma CGCM2 simulation result based on SRES A2 and B2 scenario (2030s, 2060s, 2090s) of IPCC and data were downscaled by Stochastic Spatio-Temporal Random Cascade Model (SST-RCM) technique, the model showed that the future runoff ratio was predicted from 13% to 34% while the runoff ratio of 1999-2002 was 59%. On the other hand, the impact on runoff ratio by land use change showed about 0.1% to 1% increase.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3B
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• pp.261-270
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• 2008

Even though there is a great deal of progress in a numerical method of high caliber like SPH, it is very rarely deployed in a water resources community. Despite the great stride in computing environment, depth averaged approach like a nonlinear shallow equation is still efficient tool for flood routing in large watershed, but it can give some misleading information like the inundation height of flood. In this rationale, we numerically simulate the flow into the dry channel, dry channel with an obstacle triggered by the collapse of a two dimensional water column using SPH (Smoothed Particle Hydrodynamics) in order to boost the application of numerical method of high caliber like SPH in a water resources community. As a most severe test of the robustness of SPH, we also carry out the simulation of the flow through a clearance into the wet channel driven by the rapid removal of a water gate. As a hydrodynamic model, we used the Navier-Stokes equation, a numerical integration of which was carried out using SPH. To verify the validity of newly proposed numerical model, we compare the numerically simulated flow with the others in the literature mainly from VOF and MAC, and hydraulic experiments by Martin and Moyce (1952), Koshizuka et al. (1995) and Janosi et al. (2004). It was shown that agreements between the numerical results in this study and hydraulic experiments are remarkable.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3B
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• pp.283-296
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• 2008

The Urban Stream Assessment Technique (USAT) was suggested to give information about present urban stream condition. Domestic and foreign stream evaluation methods were analyzed and some streams were previously investigated to decide evaluation factors that could evaluate stream condition and have concern with characteristics and flood control of urban stream. The USAT consisted of three steps. High step has three characteristics concerned with functions of stream such as flood risk, stream, and ecology. In middle step, three characteristics were subdivided by ten features to describe changes and degradations of urban stream. Low step consisted of fifty three factors that explain the present condition of ten features. A survey of river experts was conducted to reflect weight among characteristics and features. The weights were calculated by analytic hierarchy process(AHP). The USAT was carried out to check over application of that in Suwon, Anyang, and Joongrang stream. The results of stream evaluation were expressed by factor index, feature index, characteristic index, total index, and evaluation grade. The results of the USAT were useful to realize changed and degraded areas. It is expected that the USAT can be used as base investigation for restoring and managing urban streams.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2D
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• pp.235-242
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• 2008

Due to the lack of judgement in an information processing on road sign, older drivers usually are having a hard time driving than young group. Furthermore, according to increasing in aging population, older drivers in Korea have been growing much faster. That means research for older drivers' characteristics and the number of guide name for road sign should be needed. In accordance with suggestions, this study was carried out the number of guide names for road sign with a variety of ages from the twenties to the seventies. For the sake of this study, statistical verification was conducted to confirm a change of speed, a reading time and a misreading rate with Driving Simulator and Electrooculogram tool. As the results of study, change of speed in the age range has shown that the higher the proportion of age, the lower the rate of velocity. Also reading time in the age range with regression analysis found that the higher the proportion of age, the higher the rate of reading time by 0.106sec. Finally, a binary logistic model was used to find the main factors. As the results, 4 number of guide names for road sign have been the best of them for older driver. The result of this study verified the importance of ideal guide numbers on road sign for older driver and proved itself to be an effective method to determine the road safety for the road signs.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.7
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• pp.315-324
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• 2023

A simple and accurate whole body rehabilitation interaction technology using immersive digital content is needed for elderly patients with steadily increasing age-related diseases. In this study, we introduce whole-body interaction technology using HoloLens and Kinect for this purpose. To achieve this, we propose three coordinate transformation methods: mesh feature point-based transformation, AR marker-based transformation, and body recognition-based transformation. The mesh feature point-based transformation aligns the coordinate system by designating three feature points on the spatial mesh and using a transform matrix. This method requires manual work and has lower usability, but has relatively high accuracy of 8.5mm. The AR marker-based method uses AR and QR markers recognized by HoloLens and Kinect simultaneously to achieve a compliant accuracy of 11.2mm. The body recognition-based transformation aligns the coordinate system by using the position of the head or HMD recognized by both devices and the position of both hands or controllers. This method has lower accuracy, but does not require additional tools or manual work, making it more user-friendly. Additionally, we reduced the error by more than 10% using RANSAC as a post-processing technique. These three methods can be selectively applied depending on the usability and accuracy required for the content. In this study, we validated this technology by applying it to the "Thunder Punch" and rehabilitation therapy content.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.7
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• pp.325-332
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• 2023

Currently, the world's population has already entered a super-aging era, and the rate is expected to increase rapidly to about 40% by 2050. However, the rapid development of automation technology and the online service sector, the main technologies of the Fourth Industrial Revolution, are still further isolating them in a world where many inconveniences and development technologies are applied. As such, alienation in daily life is widely expanded in various fields, but the financial service sector is one of the must-use areas regardless of age because of its strong nature in the public service sector, and is a very important factor in the period when branches are rapidly decreasing. However, the current utilization rate of mobile banking services is not around 5%, so users over 60 are rarely able to use them. The UX design of the most frequently used remittance service screen in mobile banking services was proposed, and the difficulty of trying to find the preferred bank among 56 or more banks was solved by analyzing the usage rate of each bank and dividing it into three stages by age group from 50 or older. In addition, it was designed to strengthen customized services by showing their recently used banks as the top priority. The design proposed in this study obtained an average of 4.8 points or more out of 5 points as a result of usability satisfaction through interviews with less than 50 senior groups. This study is believed to help each bank upgrade its different mobile banking designs in a unified manner.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.7
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• pp.295-302
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• 2023

Software requirements written in natural language may have different meanings from the stakeholders' viewpoint. When designing an architecture based on quality attributes, it is necessary to accurately classify quality attribute requirements because the efficient design is possible only when appropriate architectural tactics for each quality attribute are selected. As a result, although many natural language processing models have been studied for the classification of requirements, which is a high-cost task, few topics improve classification performance with the imbalanced quality attribute datasets. In this study, we first show that the classification model can automatically classify the Korean requirement dataset through experiments. Based on these results, we explain that data augmentation through EDA(Easy Data Augmentation) techniques and undersampling strategies can improve the imbalance of quality attribute datasets, and show that they are effective in classifying requirements. The results improved by 5.24%p on F1-score, indicating that handling imbalanced data helps classify Korean requirements of classification models. Furthermore, detailed experiments of EDA illustrate operations that help improve classification performance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4D
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• pp.671-678
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• 2006

In this study, to describe vehicle-structure dynamic interaction phenomena with 1/4 vehicle model, nonlinear Hertzian contact spring and nonlinear contact damper are adopted. The external loads acting on 1/4 vehicle model are selfweight of vehicle and geometry information of running surface. The constraint equation on contact surface is implemented by the Penalty method with stabilization and the reaction from constraint violation. To describe pitching motion of various vehicles two types of the displacement constraint equations are exerted to connect between car bodies and between bogie frames, i.e., the rigid body connection and the rigid body connection with pin, respectively. For the time integration of dynamic equations of vehicles and structure Newmark time integration scheme is adopted. To reduce the error caused by inadequate time step size, adaptive time-stepping technique is also adopted. Thus, it is expected that more versatile dynamic interaction phenomena can be described by this approach and it can be applied to various railway dynamic problems with low computational cost.