• Journal of Korean Society of Water and Wastewater
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• v.25 no.6
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• pp.825-837
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• 2011

Seonakdong river consists of stagnant sections whose flowrate is controlled by the Daejeo and Noksan gates. As a result, there is not a minimum flow during normal times. The Daejeo and Noksan gates are located at the upstream head and the downstream end of Seonakdong river, respectively. Seonakdong river is an estuarine tributary of Nakdong river, which is a reservoir-like river used for agricultural irrigation, with the gate at the estuary of the river to prevent the intrusion of saline. Since the construction of the water gates, the water quality of the river has become degraded. This could also be due to the internal loading of pollutants, especially nutrients, from the sediments of the river because of the elongated detention time by the water gates. This study was thus conducted for the purpose of evaluating the current hydrologic-cycle system and providing measures for the rehabilitation of the hydrologic cycle. In this research, the daily outflow in Seonakdong River was simulated using the SWAT and SWMM models, and the water quality concentration including BOD, SS, TN, and TP were analyzed. The possibility of the application of SWAT-SWMM hybrid simulation was determined through the verification of both models. The error analysis shows that the results of both SWAT and SWAT-SWMM simulations make good agreements with those of field observations. For the single simulation results of SWAT, $R^{2}$ and NSE are 0.758, 0.511, respectively. For the hybrid simulation results of SWAT-SWMM, those are 0.880, 0.452, which means that the hybrid simulation can give more accurate results for the watershed where both the agricultural and urban areas exist.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.9
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• pp.50-57
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• 2011

Conventional bus system architectures are composed of several components such as master, arbiter, decoder and slave modules. The arbiter plays a role in bus arbitration according to the selected arbitration method, since several masters cannot use the bus concurrently. Typical priority strategies used in high performance arbiters include static priority, round robin, TDMA and lottery. Typical arbitration algorithms always consider the bus priority primarily, while the bus utilization is always ignored. In this paper, we propose an arbitration method using bus utilization for the operating block of each master. We verify the performance compared with the other arbitration methods through the TLM(Transaction Level Model). Based on the performance verification, the conventional fixed priority and round-robin arbitration methods cannot set the bus utilization. Whereas, in the case of the conventional TDMA and lottery arbitration methods, more than 100,000 cycles of bus utilization can be set by the user, exhibiting differences of actual bus utilization up to 50% and 70%, respectively. On the other hand, we confirm that for the proposed arbitration method, the matched bus utilization set by the user was above 99% using approximately 1,000 cycles.

• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.29-40
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• 2013

Seismic response of single degree of freedom system supported by shallow foundation was analyzed by using nonlinear explicit finite difference element code. Numerical analysis results were verified with dynamic centrifuge test results of the same soil profile and structural dimensions with the numerical analysis model at a centrifugal acceleration of 20 g. Differences between the analysis and the test results induced by the boundary conditions of control points can be reduced by adding additional local damping to the natural born cyclic hysteretic damping of the soil strata. The analysis results show good agreement with the test results in terms of both time histories and response spectra. Thus, it can be concluded that the nonlinear explicit finite difference element code will be a useful technique for estimating seismic residual displacement, earthpressure etc. which are difficult to measure during laboratory tests and real earthquake.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.121-130
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• 2012

This study develops the evaluation model which is for assessing on the side of users in expressway service areas. The direction of development on Evaluation Criteria is all about on the side of necessity of service area users, the reflection of current conditions, the construction of total evaluation criteria, and the examination of connecting study with current study. After that, this study examines previous evaluation criterias and researchers will select the primary provision of evaluation through FGI, and they derive the final evaluation criteria throughout the verification of suitability on Evaluation Criteria. Throughout AHP analysis which is a professional survey system of users, researchers derive on the side of facilities, on the side of operations, on the side of environments, and on the side of services in order by the weightings.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.6_1
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• pp.545-555
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• 2007

3D buildings are the most prominent feature comprising urban scene. A few of mega-cities in the globe are virtually reconstructed in photo-realistic 3D models, which becomes accessible by the public through the state-of-the-art online mapping services. A lot of research efforts have been made to develop automatic reconstruction technique of large-scale 3D building models from remotely sensed data. However, existing methods still produce irregular building polygons due to errors induced partly by uncalibrated sensor system, scene complexity and partly inappropriate sensor resolution to observed object scales. Thus, a geometric regularization technique is urgently required to rectify such irregular building polygons that are quickly captured from low sensory data. This paper aims to develop a new method for regularizing noise building outlines extracted from airborne LiDAR data, and to evaluate its performance in comparison with existing methods. These include Douglas-Peucker's polyline simplication, total least-squared adjustment, model hypothesis-verification, and rule-based rectification. Based on Minimum Description Length (MDL) principal, a new objective function, Geometric Minimum Description Length (GMDL), to regularize geometric noises is introduced to enhance the repetition of identical line directionality, regular angle transition and to minimize the number of vertices used. After generating hypothetical regularized models, a global optimum of the geometric regularity is achieved by verifying the entire solution space. A comparative evaluation of the proposed geometric regulator is conducted using both simulated and real building vectors with various levels of noise. The results show that the GMDL outperforms the selected existing algorithms at the most of noise levels.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.419-433
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• 2009

Pressure grouting is a common technique in geotechnical engineering to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressure grouting has been applied to a soil-nailing system which is widely used to improve slope stability. The soil-nailing design has been empirically performed in most geotechnical applications because the interaction between pressurized grouting paste and the adjacent ground mass is complicated and difficult to analyze. The purpose of this study is to analyze the increase of pullout resistance induced by pressurized grouting with the aid of performing laboratory model tests and field tests. In this paper, two main causes of pullout resistance increases induced by pressurized grouting were verified: the increase of residual stress; and the increase of coefficient of pullout friction. From the laboratory tests, it was found that residual stress in borehole increases by pressurized grouting and dilatancy angle could be estimated by cavity expansion theory using the measured wall displacements. From the field test results, the pullout resistance of soil-nailing with pressurized grouting was found to be 10% larger than that of soil-nailing with gravitational grouting, mainly caused by mean normal stress increase and dilatancy effect. So, the pullout resistance could be estimated by considering these two effects. The radial displacement increases with dilatancy angle increase and the dilatancy angle decreases with injection pressure increase. The measured pullout resistance obtained from field tests is in good agreement with the estimated one from the cavity expansion theory.

• Smart Structures and Systems
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• v.6 no.9
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• pp.1057-1077
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• 2010

An early detection of structural damages is critical for the decision making of repair and replacement maintenance in order to guarantee a specified structural reliability. Consequently, the structural damage detection, based on vibration data measured from the structural health monitoring (SHM) system, has received considerable attention recently. The traditional time-domain analysis techniques, such as the least square estimation (LSE) method and the extended Kalman filter (EKF) approach, require that all the external excitations (inputs) be available, which may not be the case for some SHM systems. Recently, these two approaches have been extended to cover the general case where some of the external excitations (inputs) are not measured, referred to as the adaptive LSE with unknown inputs (ALSE-UI) and the adaptive EKF with unknown inputs (AEKF-UI). Also, new analysis methods, referred to as the adaptive sequential non-linear least-square estimation with unknown inputs and unknown outputs (ASNLSE-UI-UO) and the adaptive quadratic sum-squares error with unknown inputs (AQSSE-UI), have been proposed for the damage tracking of structures when some of the acceleration responses are not measured and the external excitations are not available. In this paper, these newly proposed analysis methods will be compared in terms of accuracy, convergence and efficiency, for damage identification of structures based on experimental data obtained through a series of laboratory tests using a scaled 3-story building model with white noise excitations. The capability of the ALSE-UI, AEKF-UI, ASNLSE-UI-UO and AQSSE-UI approaches in tracking the structural damages will be demonstrated and compared.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.3
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• pp.192-203
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• 2012

As a leading nation of ubiquitous technology, South Korea has been promoting u-City pilot projects throughout the country. According to 'Fundamental Construction Law of u-City,' u-City projects are classified into old-town and new-town types. However, most projects have focused only on the new-town type. Pushing forward large-scale land development projects, Korea Land and Housing Corporation (LH Co.) under Ministry of Land Transport and Maritime Affairs (MLTM) has gained a development profit out of the u-City infrastructure and then donated the infrastructure to a local government without making any plan for operations. In the process of u-City pilot projects, old-towns have been relatively ignored and various of unexpected problems have emerged. Building the u-City of an old-town is not easy due to many constraints such as huge initial investment, long validity and verification procedures, lack of useful services for citizens, lack of professional outsourcing methods for business promotion, high operating costs of the integrated control center, inadequate law related, insufficient institutional requirements and so on. This paper introduces a case study on u-City development for an old-town, Ansan City, as a private investment project. The case will help boost u-City projects for old-towns by solving their problems and providing an effective operational mechanism. As the first BTL (Build-Transfer-Lease) project for constructing u-City, 'Broadband Information Network Development Project' of Ansan City will provide a reference model of expanding u-City projects for other cities.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.1
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• pp.19-24
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• 2015

The economic efficiency for fishery products can be related to their freshness and the quality. In order to freshly storage the product, freezing equipment system is necessary for fishing vessels. For this purpose, the horizontal plate freezer (HPF) is mostly used. In this research, our major objective is to improve the freezing performance of the HPF. Therefore, it is important to analyse the relationship between the shape of channels and the cooling temperature of the HPF. In order to save calculation time while checking the trend analysis between shape and performance, we used scaled models, and evaluate the cooling temperature of full scale model based on trend analysis results. The produced HPF in domestic was used, and the same operating conditions are considered. Based on this paper, the future research will be a comparison and verification through the experiments.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.225-232
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• 2008

AWS (all wheel steering) is applied to improve the stability and the turning performance. Most automotive cars are mainly controlled by FWS (front wheel steering) system except some cars which are made to improve their stability by using AWS. Articulated vehicles with a pivoting joint for easy turn are difficult to make a sharp turn because of the long body and long wheelbase. Therefore applying AWS to the articulated vehicles is effective to reduce the turning radius. The AWS control method for the articulated vehicles is currently applied to only Phileas vehicles which were developed by APTS. The paper on the design of a controller to guide an articulated vehicle along the path was published but control algorithm for manual driving has not been reported. In the present paper, steering, characteristics of the Phileas vehicles have been analyzed and then new algorithm has been proposed. To verify the AWS algorithm, Commercial S/W, ADAMS was used for validity of the dynamic model and algorithm.