• Journal of Korea Water Resources Association
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• v.48 no.9
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• pp.695-709
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• 2015

The inflow of nonpoint pollution sources due to sustainable development and urbanization is gradually increasing and causes a diversity of water pollution. There are lots of difficulties to find a solution as the problems related to variation of hydrological and natural phenomenon. A differentiated method to estimate the nonpoint pollution sources has been proposed using rainfall and characteristics of urbanization and observed data from sewage treatment districts in the study. The types of nonpoint pollution sources on an assumption of combined sewer system have been classified as three types which are inflow of rainfall, bypass of sewage treatments, and combined sewer overflows from a river. Three types for estimation of nonpoint pollution sources applied more accurately to generate a amount of nonpoint pollution loads. This study is expecting a wide application for effective water resource management on TMDL (total maximum delivery load) unit watershed and sewage treatment districts.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.241-241
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• 2021

Recent developments recommend the use of SSS to prevent combined sewer overflows and reduce excessive pollutant deposition in the receiving waters; however, other studies also suggest that SSS have minimal or no advantage over CSS in terms of reducing the pollutant loads being discharged in natural waterways. This study was conducted to evaluate the effectiveness of employing SSS in improving the water quality of the rivers in Okcheon-gun, South Korea. The former combined sewer outfalls (CSOs) were monitored to determine the presence of illicit connections or leaks in the newly-established SSS. Dry and wet-day monitoring was conducted alongside the collection of water samples on 14 points along the reach of the rivers and four former CSOs to determine water quality changes and patterns of pollutant loading. Among the 34 former CSOs in the study area, eight former CSOs exhibited dry-day discharges, implying the possibility of having illicit connections, leaks, or illegal wastewater discharge in the system. Moreover, relatively high biochemical oxygen demand (BOD) chemical oxygen demand (COD) concentrations, ranging from 4.8 mg/L to 24.9 mg/L and 6.4 mg/L to 10.1 mg/L, respectively were observed on three out of the four monitored CSOs. Fluctuations in the pollutant concentrations in the different monitored points along the river was also observed due to the presence of pipes discharging polluted water. Ultimately, further studies are necessary to identify the sources of dry-day discharges in the CSOs to successfully improve the water quality of the rivers in the area.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.129-142
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• 2005

A semi-monocoque truncated cone structure, which is a main structure for the payload adapter of KSLV-I, was designed. Static test was performed to confirm the reliability of the cone structure under the design loads. Strains and displacements are measured during four load cases; the compressive axial, pure bending, pure shear, and combined loading conditions. The results showed that the cone structure satisfies the design requirements. An equivalent axial load was applied to the cone structure so that the global buckling of the cone structure occurred. The measured buckling load was compared with the predicted one by finite element method. The results show a good agreement.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2317-2322
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• 2011

In three-phase power, when the power is supplied to the single phase load, there is the unbalance of load in the three-phase power. So the scott transformer is used in the power system to supply a single phase load in three-phase power without the unbalance of loads. Especially, the scott transformer is used in the AC substation of electric railroad. Two single phase transformers are combined by T-wiring in the scott transformer. So, two single phase voltage is provided by differing $90^{\circ}$ phase in three-phase power. The selection of related equipment and correction of protective relay are not easy from characteristic of the scott transformer when shunt and ground faults occur. In this paper, electric model of the scott transformer is suggested and the current of the scott transformer in shunt and ground faults is analyzed. Also, the scott transformer model is demonstrated by using Sinulink.

• ETRI Journal
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• v.35 no.3
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• pp.550-553
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• 2013

Due to limited spectrum resources and differences in link loads, network congestion is one of the key issues in cognitive radio wireless mesh networks. In this letter, a congestion avoidance model with power control, channel allocation, and routing under the signal-to-interference-and-noise ratio is presented. As a contribution, a nested optimization scheme combined with a genetic algorithm and linear programming solver is proposed. Extensive simulation results are presented to demonstrate the effectiveness of our algorithm.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.217-224
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• 2005

A higher order zig-zag shell theory is developed to refine the predictions of the mechanical and thermal behaviors partially coupled. The in-plane displacement fields are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field through the thickness. Smooth parabolic distribution through the thickness is assumed in the out-of-plane displacement in order to consider transverse normal deformation and stress. The layer-dependent degrees of freedom of displacement fields are expressed in terms of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses. Thus the proposed theory has only seven primary unknowns and they do not depend upon the number of layers. In the description of geometry and deformation of shell surface, all rigorous exact expressions are used. Through the numerical examples of partially coupled analysis, the accuracy and efficiency of the present theory are demonstrated. The present theory is suitable in the predictions of deformation and stresses of thick composite shell under mechanical and thermal loads combined.

• Computers and Concrete
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• v.14 no.6
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• pp.657-674
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• 2014

The purpose of this paper is to present a numerical procedure to analyse reinforced concrete columns subjected to combined axial loads and bending that rigorously considers nonlinear material and nonlinear geometric characteristics. Column design and stability analysis are simultaneously regarded. A finite element method is used for calculating displacements and the material and geometric nonlinearities are taken into account using an iterative process. A computer program is developed from the proposed numerical procedure, and the efficiency of the program is verified against available experimental data. The model applies to constant rectangular cross sectional columns with symmetric reinforcement distribution.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.9
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• pp.513-520
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• 2004

In the paper, we summarize the result of the experimental research for the overload criteria of domestic distribution transformers considering the electric consumption patterns of customers. For the basic characteristic data of distribution transformer overload, the actual experiments are accomplished. The field data of loads are surveyed from sample transformers for analyzing the consumption pattern of customer load. The load data acquisition devices are equipped, and the algorithm of load pattern classification is applied. In addition to this efforts, various load pattern data. in past are gathered. Then the representative load pattern of each customer type in domestic is extracted. The final results of overload criterions are presented as tabular form through the results of experiments and survey are combined. The field test of the experiment results is peformed using the special manufactured transformers, which can measure both the load and top-oil temperature of transformer. Through this, we verify that the results of field test are similar to the laboratory one and the Proposed overload criteria can be effectively applied to the real system.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.145-150
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• 2001

With the increase in the use of High-Strength Concrete(HSC) despite the its weakness like brittle characteristic, it is important to improve the performance of HSC columns, nowadays. Therefore, it is common to use higher strength steel in HSC for the purpose of ductility and strength improvement. This experimental study was set up to investigate the inelastic behavior of HSC(700kg/$cm^{2}$) columns subjected to combined axial and repeated lateral loads. Effects of key variables such as the volumetric ratio of transverse reinforcement, tie configuration and tie yield strength are studied in this research program. Test results indicate that inelastic response of HSC columns improve with proper confinement of core concrete. Increasing the amount of transverse reiuorement results in increased ductility.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.4
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• pp.263-268
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• 2006

This paper presents a real-time verification system by extracting a features of multimodal biometrics using hybrid method, which is combined the moment balance and the independent component analysis(ICA). The moment balance is applied to reduce the computation loads by extracting the validity signal due to exclude the needless backgrounds of multimodal biometrics. ICA is also applied to increase the verification performance by removing the overlapping signals due to extract the statistically independent basis of signals. Multimodal biometrics are used both the faces and the fingerprints which are acquired by Web camera and acquisition device, respectively. The proposed system has been applied to the fusion problems of 48 faces and 48 fingerprints(24 persons * 2 scenes) of 320*240 pixels, respectively. The experimental results show that the proposed system has a superior verification performances(speed, rate).