• Journal of Korea Water Resources Association
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• v.56 no.1
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• pp.45-52
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• 2023

Due to natural disasters such as heavy rain that occurred in the metropolitan area in August 2022, human casualties and property damage are increasing. Accordingly, the government is making efforts to respond to natural disasters, but due to the absence of related standards and standardized standards, problems such as increased construction costs and deterioration in construction quality for disaster prevention facility maintenance projects are occurring. Accordingly, a rough construction cost estimation module was developed and applied to 25 new pumping stations in Korea. As a result of the analysis, the accuracy of the rough construction cost derived through the module recorded 70% of the detailed design cost, which is 4% higher than the previously used rough construction cost accuracy of 66% by the Ministry of Environment. Accordingly, it is expected that the efficiency of the disaster prevention project can be increased if the developed module is used to calculate the rough construction cost for storm and flood disaster prevention in the future.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.230-233
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• 2006

Conventionally, it used to be focused on simply prevention of further settlement of structures, where, much of problems were raised and sometimes the construction itself was not possible. Further, rough estimation of the ground, which is unseen, often incurred many troubles in the maintenance. D-ROG method is a high-tech technology that changes almost all of the concepts on the conventional grouting, is expanding its application scope spanning from the restoration of settled structures to ground strengthening works necessary for building enlargement and remodeling.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.973-975
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• 2016

In this paper, we propose a selective extended Kalman filter based accurate pose estimation of the rigid body using a sensor fusion method. The pose of a rigid body can be estimated roughly by the Gauss-Newton method using the acceleration data and geomagnetic data, which can be refined with vision information and the gyro sensor information. However strong external interference noise makes the rough pose estimation difficult. In this paper, according to the measurement level of the external interference noise, the extended Kalman filter selectively uses mostly vision and gyro sensor information to increase the estimation credibility under strong interference noise environment.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.1
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• pp.8-20
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• 1999

In this paper, a design and estimation procedure for the stochastically dependent nonstationary multiple acceptance sampling plans is developed. At first, the rough-cut acceptance and rejection numbers are given as an initial solution from the corresponding sequential sampling plan. A Monte-Carlo algorithm is used to find the acceptance and rejection probabilities of a lot. The conditional probability formula for a sample path is found. The acceptance and rejection probabilities are found when a decision boundary is given. Several decision criteria and the design procedure to select optimal plans are suggested. The formula for measuring performance of these sampling plans is developed. Type I and II error probabilities are also estimated. As a special case, by setting the stage size as 1 in a dependent sampling plan, a sequential sampling plan satisfying type I and II error probabilities is more accurate and a smaller average sample number can be found. In a numerical example, a Polya dependent process is examined. The sampling performances are shown to compare the selection scheme and the effect of the change of the dependency factor.

• International Journal of Contents
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• v.9 no.1
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• pp.6-10
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• 2013

Foreground estimation in object segmentation has been an important issue for last few decades. In this paper we propose a GrabCut based automatic foreground estimation method using block clustering. GrabCut is one of popular algorithms for image segmentation in 2D image. However GrabCut is semi-automatic algorithm. So it requires the user input a rough boundary for foreground and background. Typically, the user draws a rectangle around the object of interest manually. The goal of proposed method is to generate an initial rectangle automatically. In order to create initial rectangle, we use Gabor filter and Saliency map and then we use 4 features (amount of area, variance, amount of class with boundary area, amount of class with saliency map) to categorize foreground and background. From the experimental results, our proposed algorithm can achieve satisfactory accuracy in object segmentation without any prior information by the user.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.142-147
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• 2008

Limited fossil fuels and unstable energy supply are considered as one of the critical problems in architecture requiring large amounts of energy. In order to this challenge, environment-friendly architecture design is required. Especially, Application of solar energy as a clean energy source and one kind of renewable energy. Many sites however are mainly concentrated in the developed countries, and are scarcer within the developing world. Simple radiation estimation models using meteorologically observed input parameters are often used in the applications requiring rough estimations of solar radiation. In this paper, measurements of global solar radiation and cloud data hours in climatological locations in South Korea are used to develop an estimation in solar radiation. The results of measured data are compared with the results obtained from equations, internationally accepted correlations.

• Geomechanics and Engineering
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• v.17 no.1
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• pp.11-18
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• 2019

The formulas offered so far on the settlement of raft footings provide only a rough estimate of the actual settlement. One of the best ways to make an accurate estimation is to conduct 3-dimensional finite element analyses. However, the required procedure for these analyses is comparatively cumbersome and expensive and needs a bit more expertise. In order to address this issue, in this study, a raft footing settlement formula was developed based on ninety finite element model configurations. The formula was derived using multi-parameter exponential regression analyses. The settlement formula incorporates the dimensions and the elastic modulus of a rectangular raft, vertical uniform pressure and soil moduli and Poisson's ratios up to 5 layers. In addition to this, an equation was offered for the estimation of average deflection of the raft. The proposed formula was checked against 3 well-documented case studies. The formula that is derived from 3D finite element analyses is useful in optimising the raft properties.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.353-362
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• 2009

In the process of turbine modernizations, the investigation of the influences of water passage roughness on radial flow machine performance is crucial and validates the efficiency step up between reduced scale model and prototype. This study presents the specific losses per component of a Francis turbine, which are estimated by CFD simulation. Simulations are performed for different water passage surface roughness heights, which represents the equivalent sand grain roughness height. As a result, the boundary layer logarithmic velocity profile still exists for rough walls, but moves closer to the wall. Consequently, the wall friction depends not only on roughness height but also on its shape and distribution. The specific losses are determined by CFD numerical simulations for each component of the prototype, taking into account its own specific sand grain roughness height. The model efficiency step up between reduced scale model and prototype value is finally computed by the assessment of specific losses on prototype and by evaluating specific losses for a reduced scale model with smooth walls. Furthermore, surveys of rough walls of each component were performed during the geometry recovery on the prototype and comparisons are made with experimental data from the EPFL Laboratory for Hydraulic Machines reduced scale model measurements. This study underlines that if rough walls are considered, the CFD approach estimates well the local friction loss coefficient. It is clear that by considering sand grain roughness heights in CFD simulations, its forms a significant part of the global performance estimation. The availability of the efficiency field measurements provides an unique opportunity to assess the CFD method in view of a systematic approach for turbine modernization step up evaluation. Moreover, this paper states that CFD is a very promising tool for future evaluation of turbine performance transposition from the scale model to the prototype.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.153-168
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• 1993

The ship sailing among waves suffers from the various wave loads that comes from its motion throughout its life. In the rationally-based design, the dynamic structural analysis is carried out using dynamic wave loads provided from the results of the ship motion calculation as the rigid body. This method is based on the linear theory assumed low wave height and small amplitude of motion. But at the rough sea condition, relatively high wave compared to the height ship's depth is induced the large ship motion, so configuration of the ship section below waterline changes rapidly at each time. This re-sults in a non-linear problem. Considering above situation we have already introduced the non-linear dynamic strength analysis method for the hull girder(refer vol. 29. No.4 November, 1992, Journal of SNAK). In this paper, estimation of the hull girder strength for various ship types such as tankers, containers and log carriers is carried out based on the introduced non-linear method. We expect that the results will be used as useful basic data for the es-timation of dynamic strength of ships in the rough sea.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.119-127
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• 2014

An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.