• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.260-260
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• 2011

SWAT is semi-distributed and continuous-time distributed simulation watershed model, which can simulate point and nonpoint source pollutants as well as hydrology and water quality. It was developed to predict the effects of alternative management decisions on water, sediment, and chemical yields with reasonable accuracy. It is able to predict and manage hydrology, sediments, nutrients, and pesticides with Best Management Practices (BMPs) in a watershed. SWAT model also has potential for use in ungauged basins to predict streamflow and baseflow from saturated source area in watersheds. According to various cultivation practices and climate change, SWAT model is available to analyze relative change in hydrology and water quality. In order to establish optimum management of water quality, both monitering and modeling have been conducted actively using SWAT model. As SWAT model is computer program to simulate a lot of natural phenomena, it has limitation to predict and reflect them with on hundred percent accuracy. Thus, it is possible to analyze the effect of BMPs in the watershed where users want to simulate hydrology and water quality only if model accuracy and applicability are assessed first of all and the result of it is well for the study watershed. For assessment of SWAT applicability, most researchers have used $R^2$ and Nash and Sutcliffe Efficiency (NSE). $R^2$ and NSE are likely to show different results according to a warm up period and sometimes its results are very different. There have been hardly any studies of whether warm up period can affect simulation results in SWAT model. In this study, how warm up period has a effect on SWAT results was analyzed and a appropriate warm up period was suggested. Lots of SWAT results were compared after using measured data of Soyanggang-dam watershed and applying various warm up period (0 ~ 10 year(s)). As a result of this study, when there was no warm up period, $R^2$ and NSE were 0.645, 0.602 respectively, when warm up period was 2 years, $R^2$ and NSE were 0.648, 0.632, and when warm up period was 4 years, $R^2$ and NSE were 0.663, 0.652 separately. Through this study, sensitive analysis of warm up period in SWAT model was conducted, and this study could give a guideline able to simulate hydrology and water quality for more accuracy than before as users change a lot of warm up periods as well as any simulation parameters.

• Journal of Korea Water Resources Association
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• v.42 no.5
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• pp.365-374
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• 2009

Probability plotting positions are used for the graphical display of annual maximum rainfall or flood series and the estimation of exceedance probability of those values. In addition, plotting positions allow a visual examination of the fitness of probability distribution provided by frequency analysis for a given data. Therefore, the graphical approach using plotting position has been applied to many fields of hydrology and water resources planning. In this study, the plotting position formula for the Gumbel distribution is derived by using the order statistics and the probability weight moment of the Gumbel distribution for various sample sizes. And then, the parameters of plotting position formula for the Gumbel distribution are estimated by using genetic algorithm. The appropriate plotting position formulas for the Gumbel distribution are examined by the comparison of root mean square errors and biases between theoretical reduced Gumbel variates and those calculated from derived and existing plotting position formulas. As the results, Gringorten's plotting position formula has the smaller root mean square errors and biases than any other formulas.

• Journal of Korea Water Resources Association
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• v.41 no.9
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• pp.863-872
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• 2008

In this study, a series of deposition tests have been conducted on saltwater condition(salinity 32 %o) using an annular flume, in order to estimate depositional properties of kaolinite sediments and to analyze the effect of the initial concentration on them. Total 37 deposition tests have been carried out in three different initial concentrations (1000, 5000, 15000 ppm) with varying the bed shear stress. From these test results, minimum shear stress (or critical shear stress for deposition; ${\tau}_{bmin}$) and the deposition rate parameters (${\sigma}_1,\;({\tau}^*_b-1)_{50},\;{\sigma}_2,\;t_{50}$) for kaolinite sediments have been quantified, and the effects of the initial concentration and salinity on depositional properties of cohesive sediments have been analyzed qualitatively. As the results, ${\tau}_{bmin},\;{\sigma}_1\;and\;({\tau}^*_b-1)_{50}$ are found to be 0.147, 0.74 and $0.65N/m^2$ respectively. Through comparing with results from previous studies, the performance of this study and tests results are shown to be good enough to verify.

• Journal of Korea Water Resources Association
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• v.46 no.3
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• pp.315-326
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• 2013

Despite of the importance on the maintenance of a reservoir storage, relatively few studies have addressed the stochastic reliability analysis including uncertainty on the decrease of the reservoir storage by the sedimentation. Therefore, the stochastic gamma process under the reliability framework is developed and applied to estimate the reduction of the Soyang Dam reservoir storage in this paper. Especially, in the estimation of parameters of the stochastic gamma process, the Bayesian MCMC scheme using informative prior distribution is used to incorporate a wide variety of information related with the sedimentation. The results show that the selected informative prior distribution is reasonable because the uncertainty of the posterior distribution is reduced considerably compared to that of the prior distribution. Also, the range of the expected life time of the dead storage in Soyang Dam reservoir including uncertainty is estimated from 119.3 years to 183.5 years at 5% significance level. Finally, it is suggested that the improvement of the assessment strategy in this study can provide the valuable information to the decision makers who are in charge of the maintenance of a reservoir.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.451-460
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• 2005

We present a methodology to design energy-efficient data paths using FPGAs. Our methodology integrates domain specific modeling, coarse-grained performance evaluation, design space exploration, and low-level simulation to understand the tradeoffs between energy, latency, and area. The domain specific modeling technique defines a high-level model by identifying various components and parameters specific to a domain that affect the system-wide energy dissipation. A domain is a family of architectures and corresponding algorithms for a given application kernel. The high-level model also consists of functions for estimating energy, latency, and area that facilitate tradeoff analysis. Design space exploration(DSE) analyzes the design space defined by the domain and selects a set of designs. Low-level simulations are used for accurate performance estimation for the designs selected by the DSE and also for final design selection We illustrate our methodology using a family of architectures and algorithms for matrix multiplication. The designs identified by our methodology demonstrate tradeoffs among energy, latency, and area. We compare our designs with a vendor specified matrix multiplication kernel to demonstrate the effectiveness of our methodology. To illustrate the effectiveness of our methodology, we used average power density(E/AT), energy/(area x latency), as themetric for comparison. For various problem sizes, designs obtained using our methodology are on average $25\%$ superior with respect to the E/AT performance metric, compared with the state-of-the-art designs by Xilinx. We also discuss the implementation of our methodology using the MILAN framework.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.5
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• pp.295-305
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• 2010

Although the rubble mound breakwaters in Korea have been damaged by typhoons almost every year, quantification of erosion of armor block have seldomly been made. In this paper, the damage of armor units is standardized by the relative damage. In the case where the number of damaged units is reported, it is divided by the total number of units to calculate the relative damage. In the case where the rehabilitation cost is reported, the relative damage is calculated by using its relationship with the present value of the past rehabilitation cost. The relative damage is shown to have strong correlations with the typhoon parameters such as nearest central air pressure and maximum wind speed at each site. On the other hand, the existing numerical methods for calculating the cumulative damage are compared with hydraulic model tests. The method of Melby and Kobayashi (1998) is shown to give a reasonable result, and it is used to calculate the relative damage, which is compared with the measured damage. A good agreement is shown for the East Breakwater of Yeosu Harbor, while poor agreement is shown for other breakwaters. The poor agreement may be because waves of larger height than the design height occurred due to strong typhoons associated with climate change so that the relative damage increased during the last several decades.

• The Journal of Industrial Distribution & Business
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• v.9 no.8
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• pp.41-50
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• 2018

Purpose - As an important participant in the financial markets, the commercial bank will be impacted by the interest rate marketization. Owing to the special condition of China, this paper tries to explore the impact of operating mechanisms between interest rate marketization and the profitability of the commercial Bank. Research design, data and methodology - This paper applies time series data from 2005 to 2016. Due to the short period of time series, autocorrelation often occurs. Therefore, the fully modified least squares(FMOLS) will be used to conduct an empirical analysis. The reason is that it can move off the autocorrelation between variables and disturbance term. And FMOLS also can make estimated cointegrating parameters closed to normal distribution. More importantly, in order to avoid spurious regressions, the Augmented Dickey-Fuller Test will be used to verify the stationarity of all variables. The total return of asset is treated as the profitability of commercial bank. The net interest spread is treated as a measurement of interest rate marketization. Both are regarded as dependent variables. The non-interest income or gross revenues and impaired loans or gross loans are treated as independent variables. The sixteen representative listed commercial banks are divided into three categories (state-owned, share-holding and city-owned) to conduct an estimation. Results - Via empirical analysis, the findings show that the net interest spread has a positive effect on the profitability of the commercial bank. More specifically, 1% increase in the net interest spread will lead 0.157% increase in the profitability of state-owned commercial bank, 0.269% increase in the profitability of share-holding commercial bank and 0.263% increase in the profitability of city-owned commercial bank. If regarding the sixteen listed commercial city as a whole, 1% increase in the net interest spread will lead 0.267% increase in the profitability of the commercial bank. Conclusions - As the interest rate marketization, the importance of interest rate on the profitability of commercial bank has become more and more significant. The empirical evidences also prove that the net interest spread can bring about the change of the commercial bank's profitability. Therefore, policy-makers of commercial banks should fully understand the operating mechanism between them.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.706-714
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• 2007

This study suggested a method for prediction of residual chlorine and THMs in water distribution system by measurement of residual chlorine, THMs, and other parameters, estimation of chlorine decay coefficients and THM formation coefficients, and simulation of water qualities using pipe network analysis. Bulk decay coefficients of parallel first-order were obtained by bottle tests, and pipe wall decay coefficients of first-order were estimated through evaluation of 5 models, which showed the lowest values of 0.03 for MAE(mean absolute error) and 0.037 MAE in comparison with the observed in field. And bottle tests were conducted to model first-order reaction of THM formation by nonlinear least square regression and the resultant coefficients were compared with the observed in field. As a result, the coefficients of determination$(R^2)$ for the observed and the predicted values were 0.98 in September and 0.82 in November, and the formation of THMs was predicted by modeling.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.5
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• pp.449-460
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• 2014

Since the emergence of domestically produced automobiles in 1964, the number of automobiles in circulation in South Korea has increased constantly. With this rapidly increasing number of automobiles, automobile-induced environmental pollution has become an issue of great concern, especially with regard to air pollution. Of the carbon composites contained in automobile exhaust gas, PAHs are known to be carcinogenic and highly deleterious to humans and thus need to be urgently mitigated. To address this issue of PAHs, this study was conducted to estimate qualitative of particulate PAHs contained in carbon composites in automobile exhaust gas, by capturing all particulate matter discharged from the latter. To allow for differentiated analyses, the automobiles investigated were divided into 4 groups: gasoline vehicle, motocycle, diesel vehicle, and LPG vehicle. Samples were analyzed using two methods. First, in-depth analysis was performed on organic carbon (OC) and elemental carbon (EC) composites with analysis parameters, using the Thermal Optical Transmittance Method (NIOSH 5040). Second, for the examination of particulate PAHs, GC/MSD was used to analyze the 16 PAH species specified by the Environmental Protection Agency (EPA). The analyses yielded the findings that diesel vehicles had the highest mass concentration ($2,007{\mu}g/m^3$), followed by motocycle ($1,066{\mu}g/m^3$), LPG vehicle ($392{\mu}g/m^3$), and gasoline vehicles ($270{\mu}g/m^3$). The highest carbon concentrations in total particulate matter by vehicle weight were produced from LPG vehicle (79.8%), followed by gasoline vehicle (77.4%), motocycle (69.8%), and diesel vehicle (59.1%).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.2
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• pp.105-116
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• 2004

According to the developing advanced techniques and removal of Selective Availability, much research has been conducted to improve the accuracy of GPS positioning in absolute and relative mode by estimating the nuisance parameters such as atmospheric effect, clock errors and multipath. Especially, the continuous effort of establishing the CORS in many countries and the effort of ICS making effective global networking make more application areas and the necessity of more precise location is being increased. Some of the countries like German, Japan and Swiss already utilized the Virtual Reference System for better location accuracy and services. In this study, the VRS system is investigated in terms of system principle, required H/W and S/W, management and operation, revision of related law, expected application and market etc. and find optimal solution in each aspect for economic and fast set up of the system in this country. The analysis of Korean CORS, communication infra and market estimation is performed for the efficient system establishment. Also. the suggestion on the advertisement and education of the system is also included. It is expected that this study contributes for the establishment of effective and precise nationwide location service so that many SOC areas including navigation, GIS, Telematics, LBS can provides better service for the users.