• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.349-355
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• 2017

Failures of railway systems can result in train delays or accidents, and therefore high reliability is required to ensure safety of railway systems. To improve reliability, railway systems are designed with redundant systems so that the standby system will continue to function normally even if the primary system fails. Generally, overall system reliability can be evaluated by the reliabilities of the parts of the whole system and the reliability of the redundant system considering common failures in case of each system is not conform physical, functional and process independent. In this study, the reliability of the hot-standby sparing system is analyzed the independent systems and dependent systems with common failures. The reliability for the standby system can be effectively analysed using Markov models, which can model the redundant configuration and the state transition.

• Journal of the Korea Society of Computer and Information
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• v.26 no.5
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• pp.9-16
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• 2021

In this paper, we propose a building exploration drone that can be used for a digital twin-based building control system. The existing building control system using a fixed position sensor box has a problem that a management blind spot occurs. And because people patrol themselves, it takes a lot of human resources. In this paper, a drone equipped with a temperature and humidity sensor and a gas leak detection sensor is used to search the internal path of the building centering on the control blind spot. It also aims to solve the problem of the building control system by transmitting information in real time along with the video. In addition, it has a stable hovering function using an optical floor sensor and can be applied to an existing digital twin-based building control system. The results of this study are believed to be of great help in improving the quality of digital twin control systems using drones.

• The Journal of Korean Institute of Information Technology
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• v.16 no.12
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• pp.115-125
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• 2018

The one of goals of the 2015 revised national curriculum is the successful application of achievement standards-based assessment, which assesses both the results and process of learning, ensuring that all students have achieved the educational objectives, to schools. Therefore, an achievement standards and evaluation support system is required to manage a whole process of teaching and learning based on achievement standards and provide the personalized assessment feedback to students to improve their achievement levels. In this paper, we perform a design of integrated data model and system of teaching plan, subject content, assessment plan, assessment result, and feedback data is required based on an achievement standards repository. In addition, we create a student's dashboard webpage, which representing different types of achievement of the student, and perform the comparative analysis of data models to evaluate the quality of the proposed model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.915-918
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• 2016

Virtual testing devices are required due to rapid changes in the health care industry and the increase of the medical or nursing workforce. The importance of devices such as the simulator, blood vessels, and lab equipment for modeling blood flow to the heart is increasing too. In this study, we made heart pump by using a step motor and developed device which simulates arterial, venous blood pressure, and blood flow. We finally evaluated the function of proposed device. The proposed system is composed of the pump for simulating, the valve device to describe the resistance of the artery and vein, and a reducing device showing the characteristics of the venous system. We used BOXER pump for heart simulator and silicon tube for arterial and venous vessels, and designed a reducing device. We also used the pressure sensor to measure arterial blood pressure. For the evaluation of the proposed system, we selected a range of 50~100mmHg of the blood circuit 60 per minute and then compared the blood pressure of a person and the measured blood pressure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.5
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• pp.523-532
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• 2019

Microservice architecture focuses on dividing it into small and lightweight services to build for the purpose of performing very close business functions. So it tends to concentrate only on agility, productivity, reliability, and ease of deployment of software development. Microservice architecture considers database as just a file or storage for storing and extracting data, emphasizing that data quality can be sacrificed for convenience and scalability of software development. Database reverse engineering for understanding database structure and data semantics is needed for data utilization for business decision making. However, it is difficult that reverse database engineering is applied in microservice architecture that neglects data quality. This study proposes database reverse engineering method that utilizes master data to restore the conceptual data model as a solution. The proposed method is applied to the return service database implemented by microservice architecture and verified its applicability.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.3
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• pp.101-106
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• 2004

Recently, a network defense simulator becomes essential in studying cyber incidents because the cyber terror become more and more interesting. The network defense simulator is a tool to estimate damages and an effectiveness of a defense mechanism by modeling network intrusions and defense mechanisms. Using this tool, users can find efficient ways of preventing a cyber terror and recovering from the damage. Previous simulators start the simulation after entire scenario has made and been loaded to simulation engine. However, in this way it can't model human judgement and behavior, and it can't simulate the real cyber terror very well. In this paper, we have added a dynamic simulation component to our previous network security simulator. This component improved accurate modeling of network intrusions and defense behaviors. We have also proposed new modified architecture of the simulation system. Finally we have verified correct simulation results from stammer worn simulation.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.6
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• pp.115-126
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• 2022

The purpose of this study is to try to IPA(Importance-Performance Analysis) by applying text mining approaches to user review data for korea mobile banking applications, and to derive priorities for improvement. User review data on mobile banking applications of korea commercial banks (Kookmin Bank, Shinhan Bank, Woori Bank, Hana Bank), local banks (Gyeongnam Bank, Busan Bank), and Internet banks (Kakao Bank, K-Bank, Toss) that gained from Google playstore were used. And LDA topic modeling, frequency analysis, and sentiment analysis were used to derive key attributes and measure the importance and satisfaction of each attribute. Result, although 'Authorizing service', 'Improvement of Function', 'Login', 'Speed/Connectivity', 'System/Update' and 'Banking Service' are relatively important attributes when users use mobile banking applications, their satisfaction is not at the average level, indicating that improvement is urgent.

• Geophysics and Geophysical Exploration
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• v.24 no.4
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• pp.149-157
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• 2021

Given that induced polarization (IP) and direct current (DC) resistivity surveys are similar in terms of data acquisition, most DC resistivity systems are equipped with a time-domain IP data acquisition function. In addition, the time-domain IP data include the DC resistivity values. As such, IP and DC resistivity data are intimately linked, and the inversion of IP data is a two-step process based on DC resistivity inversions. Nevertheless, IP surveys are rarely applied, in contrast to DC resistivity surveys, as proper inversion software is unavailable. In this study, through numerical modeling and inversion experiments, we analyze the problems with the conventional inverse mapping technique used to invert time-domain IP data. Furthermore, we propose a modified inverse mapping technique that can effectively suppress inversion artifacts. The performance of the technique is confirmed through inversions applied to synthetic IP data.

• Journal of the Korea Society for Simulation
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• v.32 no.3
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• pp.9-21
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• 2023

The recent conflict between Russia and Ukraine underscores the significant of military logistics support in modern warfare. Military logistics support is intricate and specialized, and traditionally centered on the mission-level operational analysis and functional models. Nevertheless, there is currently increasing demand for military logistics support even at the engagement level, especially for resupply using unmanned transport assets. In response to the demand, this study proposes a task model of the military logistics support for engagement-level analysis that relies on the logic of ammunition resupply below the battalion level. The model employs a decisions tree to establish the priority of resupply based on variables such as the enemy's level of threat and the remaining ammunition of the supported unit. The model's feasibility is demonstrated through a combat simulation using OneSAF.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.117-125
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• 2009

Recently the intelligent agent systems have been emerged as one of key issues for developing the defense M&S systems. However, most conventional agent architecture of M&S systems utilize the script-based models and can only deal with the individual behaviors so that they cannot suitably describe the precise tactical/strategic behavior and/or complex warfare environment. To overcome these problems, we have proposed the hierarchical multi-agent system architecture that is able to intelligently cope with the complex missions based on the functional role of each agent on the hierarchy such as an intelligence officer, captain, warship commander. Several simulation tests performed on 2:2 warship warfare models will illustrate our techniques.