• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.29-34
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• 2008

This study examines the effects of information and communication technologies on individual performance. The literature has paid a considerable amount of attention to social influence as a determinant of individual behavior. We combine task-technology fit with concepts from adaptive structuration theory to specify social influence. In our model, we suggest that individuals should receive support from proper social construction to have additional performance improvement. Empirical data from 317 individuals across 43 teams in 10 companies is used to assess the theoretical model. Our theoretical model received support from the data.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.3
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• pp.65-74
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• 2012

In this study, three different unit hydrograph methods (NRCS, Snyder and Clark) in the HEC-HMS were compared to find better fit with the observed data in the Namgang-Dam watershed. The Sancheong, Shinan, and Changchon in Namgang-Dam watershed were selected as the study watersheds. The input data for HEC-HMS were calculated land use, digital elevation map, stream, and watershed map provided by WAter Management Information System (WAMIS). Sixty six storms from 2004 to 2011 were selected for model calibration and validation. Three unit hydrograph methods were compared with the observed data in terms of simulated runoff volume, and peak runoff for the selected storms. The results showed that the coefficient of determination ($R^2$) for the peak runoff was 0.8295~0.9999 and root mean square error (RMSE) was 0.029~0.086 mm/day for calibration stages. In the model validation, $R^2$ for the peak runoff was 0.9061~0.9916 and RMSE was 0.030~0.088 mm/day which were more accurate than calibrated data. Analysis of variance showed that there was no significant difference among the three unit hydrograph methods.

• Water for future
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• v.29 no.6
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• pp.189-201
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• 1996

The main objective of this study is to determine the time distribution models of rainfall in Korea for estimating design floods and to suggest new runoff model(Geomorphologic Instantaneous Unit Hydrograph; GIUH) in order to be easily use the rainfall-runoff model put rainfall models practice to be suitable for the regional characteristics of hydrologic situation by practicing engineers. As a result, the reappearance of triangular hyetograph and GIUH runoff model showed promising. The historical data from about 13,000 event-rainfalls and 73 rainfall-runoff measuring data during 12 years in International Hydrological Program (IHP) basins have been used to determine the statistical factors of the time distribution for rainfalls by the Yen-Chow, Huff, Pilgrim-Cordery and Mononobe models. The Rational, Kajiyama, Nakayasu and Clark model and GIUH model that this study runoff model were used for the purpose of application limit for basin area against design concept by the estimation of flood runoff and the derivation of empirical equations to estimate the parameters for ungaged basins.

• The Journal of the Korea Contents Association
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• v.8 no.5
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• pp.123-133
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• 2008

This dissertation is a web-based cyber exhibition website and a clear difference between the general framework of the development breaks out, the cyber exhibition framework can be a model for the purpose of the proposal. The basic elements that comprise the exhibition model is archives layer, exhibit layer, and experience layer for the three-layer planed. In fact, the model has been applied throughout the analysis of cases with the application of the model presented, while others are considering goal direction also suggests the development of a cyber exhibition. If you take advantage of the cyber model of development brilliant display of the content rather than technology-driven 'material and value+media and CT' to the convergence of content through their own cyber exhibition area can expect to be recognized.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.404-411
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• 2019

In this study, the HEC-HMS was applied to determine rainfall-runoff processes for the Gokgyuchun basin. Several sub-basins have large-scale reservoirs for agricultural needs and they store large amounts of initial runoff. Three infiltration methods were implemented to reflect the effect of initial loss by reservoirs: 'SCS-CN'(Scheme I), 'SCS-CN' with simple surface method(Scheme II), and 'Initial and Constant rate'(Scheme III). Modeling processes include incorporating three different methods for loss due to infiltration, Clark's UH model for transformation, exponential recession model for baseflow, and Muskingum model for channel routing. The parameters were calibrated using an optimization technique with trial and error method. Performance measures, such as NSE, RAR, and PBIAS, were adopted to aid in the calibration processes. The model performance for those methods was evaluated at Gangcheong station, which is the outlet of study site. Good accuracy in predicting runoff volume and peak flow, and peak time was obtained using the Scheme II and III, considering the initial loss, whereas Scheme I showed low reliability for storms. Scheme III did not show good matches between observed and simulated values for storms with multi peaks. Conclusively, Scheme II provided better results for both single and multi-peak storms. The results of this study can provide a useful tool for decision makers to determine master plans for regional flood control management.

• Journal of Korea Water Resources Association
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• v.53 no.3
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• pp.155-166
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• 2020

In this study, we applied the Radar-AWS Rainrates (RAR), weather radar-based quantitative precipitation estimations (QPEs), to the Yongdam study watershed in order to perform the flood runoff simulation and calculate the inflow of the dam during flood events using hydrologic model. Since the Yongdam study watershed is a representative area of the mountainous terrain in South Korea and has a relatively large number of monitoring stations (water level/flow) and data compared to other dam watershed, an accurate analysis of the time and space variability of radar rainfall in the mountainous dam watershed can be examined in the flood modeling. HEC-HMS, which is a relatively simple model for adopting spatially distributed rainfall, was applied to the hydrological simulations using HEC-GeoHMS and ModClark method with a total of eight independent flood events that occurred during the last five years (2014 to 2018). In addition, two NCL and Python script programs are developed to process the radar-based precipitation data for the use of hydrological modeling. The results demonstrate that the RAR QPEs shows rather underestimate trends in larger values for validation against gauged observations (R² 0.86), but is an adequate input to apply flood runoff simulation efficiently for a dam watershed, showing relatively good model performance (E_NS 0.86, R² 0.87, and PBIAS 7.49%) with less requirements for the calibration of transform and routing parameters than the spatially averaged model simulations in HEC-HMS.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.3
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• pp.28-40
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• 2002

Turbulent flows around two-dimensional wing sections in ground effect are analysed by incompressible RANS equations and a finite difference method. The Baldwin-Lomax algebraic turbulence model is used to simulate high Reynolds number flows. The main purpose of this study is to clarify the two-dimensional ground effect and its flow characteristics due to different ground boundary conditions, i.e., moving and fixed bottom boundary. As a first step, to validate the present numerical code, the computational result of Clark-Y(t/C 11.7%) is compared with published numerical results and experimental data. Then, NACA4412 section in ground effect is calculated for various ground clearances with two bottom boundary conditions. According to the computational results, the difference in the lift and moment simulated with the two bottom boundary conditions is negligible, but the drag force simulated by the fixed bottom is to some extent smaller than that by the moving bottom. Therefore, it can be concluded that the drag force measured in a wind tunnel with the fixed bottom could be smaller than that with the moving bottom.

• Water Engineering Research
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• v.4 no.1
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• pp.1-17
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• 2003

A mathematical model was developed to simulate the performance of a prototype wind-powered reverse osmosis desalination system. The model consists of two sub-models operated in a series. The first sub-model is the wind-energy conversion sub-model, which has wind energy and feed water as its input and pressurized feed water as its output. The second sub-model is a reverse osmosis (RO) process sub-model, with pressurized feed water as its input and the flow and salinity of the product water or permeate as its output. Model coefficients were determined based on field experiments of a prototype wind powered RO desalination system of the University of Hawaii, from June to December 2001. The mathematical model developed by this study predicts the performance of wind-powered RO desalination systems under different design conditions. The system optimization is achieved using a linear programming approach. Based on the results of system optimization, a design guide is prepared, which can be used by both manufacturer and end-user of the wind-driven reverse osmosis system.

• Journal of Korea Water Resources Association
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• v.30 no.3
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• pp.279-291
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• 1997

This study is to evaluate the accuracy and practicality of the existing four conceptual models, two linear models of Clark and Nash model and two nonlinear models of Laruenson and WBN model, and to select an appropriate model to simulate the rainfall-runoff process in a given catchment. The variability of parameters for linear models is generally larger than that of nonlinear models. The errors in peak discharge are similar among the four conceptual models buy the errors in time to peak are quite different. Nonlinear models produce better results for time distribution than linear models. A comparison of the conceptual models to predict overall hydrograph using Friedman two-way analysis of variance by rank test indicates that nonlinear models are slightly better than linear models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.4
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• pp.489-498
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• 2016

Despite the extant quantum communication technology that does not allow copying, wiretapping, and/or monitoring, cyber-terror-attempts from hackers with unconscientious purposes and motives are prospected to persist. Hence, it is imperative and necessary to invest in studies geared toward understanding the psychology of hackers. The current study referred to Beebe & Clark (2006) and sought out the psychological variables in hackers involved in deviant hacking activities, measured the purpose of hacking and actual hacking experiences, and constructed a predictive model that can categorize hacker types based on their intentions.