• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.536-538
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• 2006

The most important factor of mobile robot is to build a map for surrounding environment and estimate its localization. This paper proposes a real-time localization and map building method through 3-D reconstruction using scale invariant feature from monocular camera. Mobile robot attached monocular camera looking wall extracts scale invariant features in each image using SIFT(Scale Invariant Feature Transform) as it follows wall. Matching is carried out by the extracted features and matching feature map that is transformed into absolute coordinates using 3-D reconstruction of point and geometrical analysis of surrounding environment build, and store it map database. After finished feature map building, the robot finds some points matched with previous feature map and find its pose by affine parameter in real time. Position error of the proposed method was maximum. 8cm and angle error was within $10^{\circ}$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.3
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• pp.215-221
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• 2012

In this paper, we introduce an optimization method to improve pursuit performance of a pursuer in a pursuit-evasion game (PEG). Pursuers build a probability map and employ a hybrid pursuit policy which combines the merits of local-max and global-max pursuit policies to search and capture evaders as soon as possible in a 2-dimensional space. We propose an episodic parameter optimization (EPO) algorithm to learn good values for the weighting parameters of a hybrid pursuit policy. The EPO algorithm is performed while many episodes of the PEG are run repeatedly and the reward of each episode is accumulated using reinforcement learning, and the candidate weighting parameter is selected in a way that maximizes the total averaged reward by using the golden section search method. We found the best pursuit policy in various situations which are the different number of evaders and the different size of spaces and analyzed results.

• Geotechnical Engineering
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• v.8 no.2
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• pp.31-44
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• 1992

The probabilistic and statistical model is used to estimate the probability of liquefaction potential and pore water pressure build up due to earthquake in fully saturated sand deposit for each case of being structure(anisotropic) or not(isotropic). To execute this paper, dynamic shear strength parameters to show the relationship between shear strength and cyclic loading under isotropic or anisotropic condition in saturated sand deposit are presented. Using these parameters, the program which Predicts Pore water Pressure build up due to earthquake is developed. Using the 3-dimensional Random Field Model considering uncertainty of resistance and strength parameter, the program which computes the probability of liquefaction potential is developed. The developed program is applied to a case study, and then the result shows that the probability of liquefaction in isotropic condition is higher than in anisotropic condition. The ratio of pore water pressure tends to decrease as Kc increases.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.4
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• pp.50-55
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• 2007

Stereolithography (SLA) is a technique using a laser beam to cure a photopolymer liquid resin with three-dimensional computer-aided design (CAD) data, The accuracy of the prototype, the build time, and the cured properties of the resins are controlled by the SLA process parameters such as the size of the laser beam, scan velocity, hatch spacing, and layer thickness, In particular, the size of the laser beam is the most important parameter in SLA, This study investigated the curing properties of photopolymers as a function of the laser beam size, The cure width and depth were measured either on a single cure line or at a single cure layer for various hatch spacings and laser beam sizes, The cure depth ranged from 0.23 to 0.34 mm and was directly proportional to the beam radius, whereas the cure width ranged from 0.42 to 1.07 mm and was inversely proportional to the beam radius, The resulting surface roughness ranged from 1.12 to $2.23{\mu}m$ for a ratio of hatch spacing to beam radius in the range 0.5-2.0 at a beam radius of 0.17 mm and a scan velocity of 125 mm/sec.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.3
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• pp.152-159
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• 2002

SLA (Stereolithography Apparatus) it a process used to rapidly produce polymer components directly from a computer representation of the part. Though SLA is being recognized as an innovative technology, it still cannot be used to fully practical application since it lacks of dimensional accuracy compared to conventional process. If the shrinkage were perfectly uniform and no distortion took place, excellent part accuracy could still be achieved through and appropriate scaling factor when generating the build file. However, in certain geometries involving intersecting thick and thin sections, nonuniform retrain shrinkage becomes the engine of part distortion. In order to improve the part accuracy of SLA, this paper evaluates how largely each parameter of SLA contributes to the part accuracy and estimates the optimal set of parameter which minimizes the dimension error of the test part, "Slab (100mm$\times$100mm$\times$2mm)"and "scale bar"part. Three control parameters such as critical exposure, generation depth and fill cure depth are used.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.171-178
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• 2018

Recently, the continuing operation of nuclear power plants has become a major controversial issue in Korea. Whether to continue to operate nuclear power plants is a matter to be determined considering many factors including social and political factors as well as economic factors. But in this paper we concentrate only on the economic factors to make an optimum decision on operating nuclear power plants. Decisions should be based on forecasts of plant accident risks and large and small accident data from power plants. We outline the structure of a decision model that incorporate accident risks. We formulate to decide whether to shutdown permanently, shutdown temporarily for maintenance, or to operate one period of time and then periodically repeat the analysis and decision process with additional information about new costs and risks. The forecasting model to predict nuclear power plant accidents is incorporated for an improved decision making. First, we build a one-period decision model and extend this theory to a multi-period model. In this paper we utilize influence diagrams as well as decision trees for modeling. And bayesian statistical approach is utilized. Many of the parameter values in this model may be set fairly subjective by decision makers. Once the parameter values have been determined, the model will be able to present the optimal decision according to that value.

• Journal of the Korea Society of Computer and Information
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• v.17 no.11
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• pp.11-18
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• 2012

Debris flow deposition model is a model to predict affected areas by debris flow and random walk model (RWM) was used to build the model. Although the model was proved to be effective in the prediction of affected areas, the model has several free parameters decided experimentally. There are several well-known methods to estimate parameters, however, they cannot be applied directly to the debris flow problem due to the small size of training data. In this paper, a modified neural network, called pseudo sample neural network (PSNN), was proposed to overcome the sample size problem. In the training phase, PSNN uses pseudo samples, which are generated using the existing samples. The pseudo samples smooth the solution space and reduce the probability of falling into a local optimum. As a result, PSNN can estimate parameter more robustly than traditional neural networks do. All of these can be proved through the experiments using artificial and real data sets.

• The Journal of Natural Sciences
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• v.13 no.1
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• pp.97-111
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• 2003

This study aims at presenting the planning parameter of ski course by designing Gapyung ski course. This site is located at Hacheon-ri, Gapyung-gun, Kyunggi-do and has an area $1,594,001m^2$. Design objectives of Gapyung Ski Resort were to build the most suitable ski course on the site area and make a comparative ski resort. This design process covers the following : site inventory and analysis; integration of design program and terrain analysis; slope planning and trail balance; comparison with other ski resort. This ski resort was composed of 5 lifts and 10 ski trails which are divided into 2 intermediate course, 3 high intermediate course, 4 advanced course, and I expert course. Total length of slope distance is 8,738m. This ski resort will be developed for advanced skiers and snow boarders who enjoy a mogul and a half pipe course. Therefore, the strategy of this ski resort is marked for target market of high intermediate.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.91-99
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• 2015

This study intends to build a traffic accident predictive model considering road geometrics, traffic and enviromental characteristics and identify the relationship of 4-legs intersection accidents in Seoul and Busan metropolitan area. The RPNB(Random Parameter Negative Binomial) model shows improvement over the fixed NB(Negative Binomial) and out of 53 variables, 10 variables (main road number of lane, main road vehicle traffic volume(left), minor road vehicle traffic volume(right), main road drive restriction, minor road sight distance, minor road median strip, minor road speed limit, minor road speed restriction) showed to have significant variables affecting traffic accident occurrences in 4-legs signilized intersections. Also, among 10 significant variables, 2 variables(minor road sight distance, minor road speed restriction) found to be random parameters.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.497-503
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• 2008

The Oxic-Settling-Anaerobic(OSA) process is a modified activated sludge processes for sludge reduction. It is evaluated that the sludge production in OSA process can decrease to 88% because of biomass decay and kinetic parameter($Y_H$ 0.237mgVSS/mgCOD, $b_H$ $0.195d^{-1}$) in anaerobic reactor, when compared with CAS process. However, it has problems caused by sludge reduction such as increase of nutrient loading. In case that the anoxic condition through the introduction of the intermittent aeration for the enhancement of nitrogen removal ability build up and enough rbCOD is suppled, maximum 88% of nitrogen is removed in the OSA process. If the OSA process optimizing the intermittent aeration cycle is applied to the separate sewage system with high rbCOD fraction, it can be converted to advanced process in terms of the sludge reduction and nitrogen removal, simultaneously.