• The Transactions of the Korea Information Processing Society
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• v.7 no.3
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• pp.935-942
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• 2000

In this paper we introduce a fast simplification algorithm for terrain height fields to produce a triangulated irregular network, based on the greedy insertion algorithm in [1,4,5]. Our algorithm partitions a terrain height data into rectangular blocks with the same size ad simplifies blocks one by one with the greedy insertion algorithm. Our algorithm references only to the points and the triangles withing each current block for adding a point into the triangulation. Therefore, the algorithm runs faster than the greedy insertion algorithm, which references all input points and triangles in the terrain. Our experiment shows that partitioning method runs from 4 to more than 20 times faster, and it approximates test height fields as accurately as the greedy insertion algorithms. Most greedy insertion algorithms suffer from elongated triangles that usually appear near the boundaries. However, we insert the four corner points into each block to produce the base triangulation of the block before the point addition step begins so that elongated triangles could not appear in th simplified terrain.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.15-21
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• 2009

This paper proposes a novel algorithm to assess the abnormal heart beats such as PVC (Premature Ventricular Contraction) and its subsequent RUNs. Our Arrhythmic detection scheme is based on only the R-R Interval features extracted from ECG waveforms and MIT-BIH arrhythmia database is evaluated to validate the efficiency of our algorithm in terms of sensitivity, specificity, FPR(%) and FNR(%).

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.35-40
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• 2003

This paper presents a method for designing layout on the yard and evaluating alternative designs of the layout by applying simulation. The method is based on the concepts of the conventional port container terminal with a perpendicular yard layout. In general, yard design of the container terminal is consists of the two major parts. One is to divide yard area between the number of sections and the number of runs and the other is to decide the number of equipment that is the yard truck and yard crane. In the past days, this design was depended on the experience of the terminal operator and the structure of the conventional terminal layout because it is a very complex decision problem. In this paper we suggest the method of yard design as a conceptual procedure and estimate the efficiency of the container crane and the optimal the number of equipment using the simulation. Numerical examples are provided in order to illustrate the conceptual procedure. As the example, the suggested method and simulation are applied to the virtual container terminal with a perpendicular yard layout. In the results, the number of sections and runs on yard area, the number of yard truck per container crane and the number of yard crane per run are decided. In additional, the traffic among blocks on yard layout is estimated in terms of rate.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.3
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• pp.52-60
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• 2019

This paper presents a numerically robust algorithm to construct a Voronoi diagram of circles in the plane. The circles are allowed to have intersections among them, but one circle cannot fully contain another circle. The Voronoi diagram is a tessellation of the plane into Voronoi regions of given circles. Each circle has its Voronoi region which is defined by a set of points in the plane closer to the circle than any other circles. The distance from a point p to a circle $c_i$ of center $p_i$ and radius $r_i$ is ${\parallel}p-p_i{\parallel}-r_i$, which is the closest Euclidean distance from p to the circle boundary. The proposed algorithm first constructs the point Voronoi diagram of centers of given circles, then it enlarges each point to the circle and expands its Voronoi region accordingly. This region-expansion process is done by local modifications and after completing this process for the whole circles the desired circle Voronoi diagram can be obtained. The proposed algorithm is numerically robust and we provide with a few examples to show its robustness. The algorithm runs in $O(n^2)$ time in the worst case and O(n) time on average where n is the number of the circles. The experiment shows that the region-expansion algorithm is robust and runs fast with strong linear time behavior.

• Membrane and Water Treatment
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• v.10 no.3
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• pp.213-221
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• 2019

Anaerobic digestion (AD) has been widely used to valorize food waste (FW) because of its ability to convert organic carbon into $CH_4$ and $CO_2$. Korean FW has a high content of fruits and vegetables, and efficient hydrolysis of less biodegradable fibers is critical for its complete stabilization by AD. This study examined the digestates from different anaerobic digesters, namely Rs, Rr, and Rm, as the inocula for the AD of vegetable waste (VW) and cellulose (CL): Rs inoculated with anaerobic sludge from an AD plant, Rr inoculated with rumen fluid, and Rm inoculated with anaerobic sludge and augmented with rumen fluid. A total of six conditions ($3\;inocula{\times}2\;substrates$) were tested in serial subcultures. Biogas yield was higher in the runs inoculated with Rm than in the other runs for both VW (up to 1.10 L/g VS added) and CL (up to 1.05 L/g VS added), and so was biogas production rate. The inocula had different microbial community structures, and both substrate type and inoculum source had a significant effect on the formation and development of microbial community structures in the subcultures. The overall results suggest that the bioaugmentation with rumen microbial consortium has good potential to enhance the anaerobic biodegradability of VW, and thereby can help more efficiently digest high fiber-content Korean FW.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.9
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• pp.1-8
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• 2022

This paper studies market efficiency from a weak form aspect using opening and closing prices of the Shanghai stock exchange composite index (SSEC) and Shenzhen stock exchange composite index (SZSEC) under the expected return theory. Classical methods (autocorrelation and runs test) are used to examine the features of stock returns, and little evidence against mutual independence of returns is found. We predict daily returns of SSEC and SZSEC with AR(p) and VAR(p) models (in this paper, p = 5 is taken as a one-week lag) and perform a virtual experiment on two indexes based on the predicted value of daily returns from AR(p) or VAR(p) model. From the results of AR(p) and VAR(p) for two indexes, we attempt to find out how the market efficiency level changes when the information from the other market is under consideration as we check the market efficiency level in one market. We find that SSEC in 2014-2016 and SZSEC in 2015-2016 are inefficient from the result of autocorrelation, that SSEC in 2016 and SZSEC in 2013 are not efficient from the result of runs test, that the stock market is efficient except 2005, 2009, 2010 and 2017 in SSEC and 2005, 2016 and 2017 in SZSEC and that SSEC is more influenced by SZSEC but SSEC influences SZSEC less from the result of the virtual experiment.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.393-399
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• 2009

This paper introduces an automated tool named Advanced Stochastic Schedule Simulation System (AS4). The system automatically integrates CPM schedule data exported from Primavera Project Planner (P3) and historical activity duration data obtained from a project data warehouse, computes the best fit probability distribution functions (PDFs) of historical activity durations, assigns the PDFs identified to respective activities, computes the optimum number of simulation runs, simulates the schedule network for the optimum number of simulation runs, and estimates the best fit PDF of project completion times (PCTs). AS4 improves the reliability of simulation-based scheduling by effectively dealing with the uncertainties of the activities' durations, increases the usability of the schedule data obtained from commercial CPM software, and effectively handles the variability of the PCTs by finding the best fit PDF of PCTs. It is designed as an easy-to-use computer tool programmed in MATLAB. AS4 encourages the use of simulation-based scheduling because it is simple to use, it simplifies the tedious and burdensome process involved in finding the PDFs of the many activities' durations and in assigning the PDFs to the many activities of a new network under modeling, and it does away with the normality assumptions used by most simulation-based scheduling systems in modeling PCTs.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.827-834
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• 2009

In respond to the demand of an open, fair, transparent, and efficient environment for procurement, many governments have incorporated the use of internet in their procurement systems with online procurement (e-procurement). Given the different policies and laws which have to be complied with, the practice of government e-procurement system varies from one country to another. Thus, experiences in running e-procurement will vary as well. The achievements and obstacles of one country's experience will be a constructive reference for other countries in establishing e-procurement system. In this regard, government e-procurement system practices in two Southeast Asia countries i.e., Thailand and Indonesia particularly in public works are consecutively presented and finally compared in this paper. The government of Thailand has applied Online Auctions (e-Auctions) as the national procurement practice since 2005 and performed the e-Auctions in two types: Reverse Auction and Sealed Bid Auction. Contrary to the common practice of e-procurement, the Thai government, with some rationales, runs the bid documents obtaining manually as well as qualification and technical documents submission and holding the e-Auctions at bidding office. Whereas Indonesian government runs Online Sealed Bid Bidding (e-Procurement) and most of the bidding stages are performed electronically except bid evaluation for both technical and financial. The advantages and drawbacks of these two e-procurement practices are discussed as well as improvements that have to be made for successful of e-procurement.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.170-181
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• 2004

DUPIC powder and pellets were successfully fabricated in accordance with the quality assurance program described in the Quality Assurance Manual for DUPIC fuel fabrication, which was developed on the basis of the CAN3-Z299.2-85 standard. This manual describes the quality management system applicable to the activities performed for DUPIC fuel fabrication. It covers the work processes, policies and procedures used for planning, executing, and verifying the work carried out for DUPIC fuel fabrication. It is important that a Quality Program is in place before the fabrication of the fuel for irradiation testing. In order to qualify the DUPIC pellet manufacturing processes, 3 series of experiments for the pre-qualification and 3 series for the qualification were performed. In these experiments, the optimum process conditions were established. Then, under the control of the QA program, 8 series of production runs were performed to make the qualified DUPIC pellets in a batch size of 1 kg. In these production runs, DUPIC fuel pellets satisfying the standard CANDU fuel pellet specifications could be successfully produced.

• Journal of the Korean earth science society
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• v.44 no.3
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• pp.185-195
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• 2023

The prolonged and heavy East Asian summer precipitation in 2020 may have been caused by an enhanced Madden-Julian Oscillation (MJO), which requires evaluation using forecast models. We examined the performance of GloSea6, an operational forecast model, in predicting the East Asian summer precipitation during July 2020, and investigated the role of MJO in the extreme rainfall event. Two experiments, CON and EXP, were conducted using different convection schemes, 6A and 5A, respectively to simulate various aspects of MJO. The EXP runs yielded stronger forecasts of East Asian precipitation for July 2020 than the CON runs, probably due to the prominent MJO realization in the former experiment. The stronger MJO created stronger moist southerly winds associated with the western North Pacific subtropical high, which led to increased precipitation. The strengthening of the MJO was found to improve the prediction accuracy of East Asian summer precipitation. However, it is important to note that this study does not discuss the impact of changes in the convection scheme on the modulation of MJO. Further research is needed to understand other factors that could strengthen the MJO and improve the forecast.