• Geomechanics and Engineering
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• v.37 no.2
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• pp.135-147
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• 2024

A GIS-based landslide susceptibility mapping (LSM) was carried out using frequency ratio (FR), modified frequency ratio (M-FR), analytic hierarchy process (AHP), and modified analytic hierarchy process (M-AHP) methods to identify and delineate the potential failure zones along the Halong - Vandon expressway. The thematic layers of various landslide causative factors were generated for modeling in GIS, including geology, rainfall, distance to fault, distance to road, slope, aspect, landuse, density of landslide, vertical relief, and horizontal relief. In addition, a landslide inventory along the road network was prepared using data provided by the management department during the course of construction and operation from 2017 to 2019, when many landslides were documented. The validation results showed that the M-FR method had the highest AUC value (AUC = 0.971), which was followed by the FR method with AUC = 0.961. The AUC values were 0.939 and 0.892 for the M-AHP and AHP methods, respectively. The generated LSM obtained from M-FR method classified the study area into five susceptibility classes: very low (0), low (0-1), moderate (1-2), high (2-3), and very high (3-4) classes, which could be useful for various stakeholders like planners, engineers, designers, and local public for future construction and maintenance in the study area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.40-45
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• 2018

Intelligent monitoring and diagnosis of production processes based on multivariate statistical methods has been one of important tasks for safety and quality issues. This is due to the fact that faults and unexpected events may have serious impacts on the operation of processes. This study proposes a diagnostic scheme based on effective representation of process measurement data and is evaluated using simulation process data. The effects of utilizing a preprocessing step and nonlinear statistical methods are also tested using fifteen faults of the simulation process. Results show that the proposed scheme produced more reliable results and outperformed other tested schemes with none of the filtering step and nonlinear methods. The proposed scheme is expected to be robust to process noises and easy to develop due to the lack of required rigorous mathematical process models or expert knowledge.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.3
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• pp.217-227
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• 1989

A process control graphic system is proposed as an efficient tool for monitoring the operation of power plant. It uses the multi-processor structure with 60 Kbyte shared memory as an implemental type of the distributed computer system, so that it is flexible, functionally extensible, and applicable to real-time process. The shared memory is used as a real-time database handling the process values and operator's commands. The database files, generated by the user-interactive graphic editor developed for the system or text editor, have the characteristics of simplicity and user-friendliness. The process control graphic system, that can monitor the operation of boiler and function as a backup controller in case of failure in boiler controller, is applied to Ulsan power plant. As a result, it displays the operating data of the boiler process without error by 14 pages of color graphic image according to the operation menu, and additionally functions well as a fault-tolerant control system.

• The KIPS Transactions:PartA
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• v.13A no.4 s.101
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• pp.289-294
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• 2006

Checkpointing is an effective mechanism that allows a process to resume its execution that was discontinued by a system failure without having to restart from the beginning. Especially, page-level incremental checkpointing saves only the modified pages of a process to minimize the checkpointing overhead. This means that in incremental checkpointing, the time consumed for checkpointing varies according to the amount of modified pages. Thus, the efficient interval of checkpointing must be determined on run-time of the process. In this paper, we present an efficient and adaptive page-level incremental checkpointing facility that is based on the cost analysis of process execution time. In our simulation, results show that the proposed mechanism significantly reduced the average process execution time compared with existing fixed-interval-based page-level incremental checkpointing.

• Journal of the Korea Society of Computer and Information
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• v.25 no.4
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• pp.47-53
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• 2020

Blockchain is a distributed shared ledger that transparently manages information through verification and agreement between nodes connected to a distributed network. Recently, cases of data management among authorized agencies based on private blockchain are increasing. In this paper, we investigated the application cases and technical processes of PBFT, the representative consensus algorithm of private blockchain, and proposed a modified PBFT algorithm that enables efficient consensus by simplifying duplicate verification and consensus processes that occur during PBFT processing. The algorithm proposed in this paper goes through the process of selecting a delegation node through an authoritative node and can increase the safety of the delegation node selection process by considering an efficient re-election algorithm for candidate nodes. By utilizing this research, it is possible to reduce the burden on the network communication cost of the consensus process and effectively process the final consensus process between nodes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1648-1653
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• 2012

In general, fault of a virtually finished product that is value-added one, since it has gone throughout the most of processes, may give rise to quality cost nearly amount to its selling price and can be a main cause that decreases the efficiency of manufacturing process. This paper proposes a dispatching algorithm for manufacturing process with quality volatilities with consideration of due-dates and required quality level. In order to evaluate the proposed algorithm, this paper examines the performance of the proposed method by comparing it with that of the existing dispatching algorithms in terms of minimizing the mean tardiness. In addition, from the perspective of process capability based on required quality level, this study shows the superiority of the proposed dispatching algorithm.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.1
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• pp.91-98
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• 2013

The rigorous requirements of modern spacecraft missions necessitate a precise attitude determination strategy. This paper mainly researches that, based on three space-borne attitude sensors: 3-axis rate gyros, 3-antenna GPS receiver and star-sensor. To obtain global attitude estimation after an information fusion process, a feedback-involved Federated Kalman Filter (FKF), consisting of two subsystem Kalman filters (Gyros/GPS and Gyros/Star-sensor), is established. In these filters, the state equation is implemented according to the spacecraft's kinematic attitude model, while the residual error models of GPS and star-sensor observed attitude are utilized, to establish two observation equations, respectively. Taking the sensors' different update rates into account, these two subsystem filters are conducted under a variable step size state prediction method. To improve the fault tolerant capacity of the attitude determination system, this paper designs malfunction warning factors, based on the principle of ${\chi}^2$ residual verification. Mathematical simulation indicates that the information fusion strategy overwhelms the disadvantages of each sensor, acquiring global attitude estimation with precision at a 2-arcsecs level. Although a subsystem encounters malfunction, FKF still reaches precise and stable accuracy. In this process, malfunction warning factors advice malfunctions correctly and effectively.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.343-346
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• 2004

This paper proposes a leakage-suppressed SRAM with dynamic power saying scheme for the future leakage-dominant sub-70-nm technology. By dynamically controlling the common source-line voltage ($V_{SL}$) of sleep cells, the sub-threshold leakage through these sleep cells can be reduced to be 1/10-1/100 due to the reverse body-bias effect, dram-induced barrier lowering (DIBL) and negative $V_{GS}$ effects. Moreover, the bit-ling leakage which mar introduce a fault during the read operation can be completely eliminated in this new SRAM. The dynamic $V_{SL}$ control can also reduce the bit-line swing during the write so that the dynamic power in write can be reduced. This new SRAM was fabricated in 0.35-${\mu}m$ CMOS process and more than $30\%$ of dynamic power saying is experimentally verified in the measurement. The leakage suppression scheme is expected to be able to reduce more than $90\%$ of total SRAM power in the future leakage-dominant 70-nm process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.9
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• pp.24-32
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• 2020

A self-blast type gas circuit breaker has been studied in this study to improve efficiency of interrupting performance of short line fault(SLF). Hot gas flows of gas circuit breaker have been simulated to evaluate interruption performance using CFD. Design parameters such as various types of expansion chamber and nozzles are suggested by using simulation results. Simulated results and experimental ones are compared with previous (ones that of in under development and with capacitor) GCB. Modified new shape of an expansion chamber and nozzle has been suggested to improve the efficiency of gas flow and to provide guidelines for designing self-blast breaker with a higher interruption capability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.1
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• pp.5-24
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• 2010

Data fusion is an attractive technology because it allows various trade-offs related to performance metrics, e.g., energy, latency, accuracy, fault-tolerance and security in wireless sensor networks (WSNs). Under a complicated environment, each sensor node must be equipped with more than one type of sensor module to monitor multi-targets, so that the complexity for the fusion process is increased due to the existence of various physical attributes. In this paper, we first investigate the process and performance of multi-attribute fusion in data gathering of WSNs, and then propose a self-adaptive threshold method to balance the different change rates of each attributive data. Furthermore, we present a method to measure the energy-conservation efficiency of multi-attribute fusion. Based on our proposed methods, we design a novel energy equilibrium routing method for WSNs, viz., multi-attribute fusion tree (MAFT). Simulation results demonstrate that MAFT achieves very good performance in terms of the network lifetime.