• Journal of KIISE
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• v.43 no.5
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• pp.531-540
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• 2016

Development of various sensors attached to mobile and wearable devices has led to increasing recognition of current context-based service to the user. In this study, we proposed a probabilistic model for recognizing user's food intake context, which can occur in a great variety of contexts. The model uses low-level sensor data from mobile and wrist-wearable devices that can be widely available in daily life. To cope with innate complexity and fuzziness in high-level activities like food intake, a context model represents the relevant contexts systematically based on 4 components of activity theory and 5 W's, and tree-structured Bayesian network recognizes the probabilistic state. To verify the proposed method, we collected 383 minutes of data from 4 people in a week and found that the proposed method outperforms the conventional machine learning methods in accuracy (93.21%). Also, we conducted a scenario-based test and investigated the effect contribution of individual components for recognition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1218-1224
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• 2017

With the increasing risk in building liquefied natural gas carriers (LNGC), pre-simulation of various scenarios is required for system integration and safe operation. In particular, the power management system (PMS) is an important part of the LNGC; it works in tight integration with the power control systems to achieve the desired performance and safety. To verify and improve unpredicted errors, we implemented a simulation model of power generation and consumption for testing PMS based on software-in-the-loop (SIL) method. To control and verify the PMS, numeric and physical simulation modeling was undertaken utilizing MATLAB/Simulink. In addition, the simulation model was verified with a load sharing test scenario for a sea trial. This simulation allows shipbuilders to participate in new value-added markets such as commissioning, installation, operation, and maintenance.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.332-338
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• 2017

Launch and recovery system(LARS) is required to perform an USV-based underwater exploration. Through the analysis of the requirements according to the scenario of underwater exploration, the mechanism of LARS and the conceptual design of the mechanical parts of LARS are carried out. In addition, a USV motion can be induced due to environmental disturbances such as waves, so the detailed design of LARS for recovering the underwater tow-fish stably in consideration of the USV motion is performed. To verify the performance of launch and recovery operations, LARS and test bed were developed. The results show that the proposed LARS can stably launch and recovery an underwater tow-fish.

• Journal of Drive and Control
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• v.13 no.4
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• pp.14-22
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• 2016

This paper presents a stochastic and predictive working-risk-assessment algorithm for excavators based on a one-layer laser scanner. The one-layer laser scanner is employed to detect objects and to estimate an object's dynamic behaviors such as the position, velocity, heading angle, and heading rate. To estimate the state variables, extended and linear Kalman filters are applied in consideration of laser-scanner information as the measurements. The excavator's working area is derived based on a kinematic analysis of the excavator's working parts. With the estimated dynamic behaviors and the kinematic analysis of the excavator's working parts, an object's behavior and the excavator's working area such as the maximum, actual, and predicted areas are computed for a working risk assessment. The four working-risk levels are defined using the predicted behavior and the working area, and the intersection-area-based quantitative-risk level has been computed. An actual test-data-based performance evaluation of the designed stochastic and predictive risk-assessment algorithm is conducted using a typical working scenario. The results show that the algorithm can evaluate the working-risk levels of the excavator during its operation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.10
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• pp.979-984
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• 2010

The users who use a combined GPS/Galileo receiver will benefit from an improved availability of the combined system and a reduced dependence on one particular positioning system. However, these users must solve the problem of an offset between the time scales of GPS and Galileo (GGTO). GGTO must be analyzed for not only a navigation system but also a timing system requesting precise time service. This paper analyzes the interoperability problem in a combined GPS/Galileo timing receiver and estimates the timing performance under various assumptions. The GPS real measurements were collected by using the commercial timing receiver from Ashtech Ltd. and the Galileo measurements were generated by a simulation software. A suitable test scenario set-up and the performance in a point of timing stability was evaluated.

• Fire Science and Engineering
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• v.16 no.1
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• pp.66-76
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• 2002

This paper includes new nozzle design, basic design factors of water mist system that minimize a thermal damage of cable causing business interruption and applying underground utility tunnel. A underground concrete structure (2.5 m(H)$\times$2.5 m(W)$\times$25 m(D)) is constructed in order to test a nozzle performance. Under the designing fire scenario, critical thermal damage of cable sheath ($400^{\circ}c$) reached within a 2 minutes with unsuppressed fire, but type 1 nozzle (SMD 470 $\mu{m}$) and type 2 nozzle (SMD 650 $\mu{m}$) control cable temperature below $400^{\circ}c$. A system performance and fundamental design factors; K factor, flow rate, spray angle, size distribution, nozzle pressure, spray density are analyzed and proposed for system optimization.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.641-650
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• 2006

There has been a continued increase in the complexity of software equipped with wireless mobile devices, due to the introduction of new device functionality and services via network connection. The increasement expected to be accelerated by convergence of telecommunication and broadcasting, and proliferation of telematics and home networking services using wireless mobile devices. The higher the complexity of mobile device software, the higher the necessity of management for the software. As for the global standard of mobile device management technology, OMA DM has been widely adopted by device manufacture and expected to be accelerated its adoption. In this paper, we present a development result of mobile device software release management system ThinkSync DM SoftMan. The implementation details of ThinkSync DM SoftMan are provided in implementation architecture and its working scenario based on the design of ThinkSync DM SoftMan that is summarized in this paper as our previous work. The conformance and performance test of the system are presented.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.8
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• pp.689-696
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• 2001

Large-scale Multi-disciplinary Systems(LMS) such as transportation, aerospace, defense etc. are complex systems in which there are many subsystems, interfaces, functions and demanding performance requirements. Because many contractors participate in the development, it is necessary to apply methods of sharing common objectives and communicating design status effectively among all of the stakeholders. The processes and methods of systems engineering which includes system requirement analysis; functional analysis; architecting; system analysis; interface control; and system specification development provide a success-oriented disciplined approach to the project. This paper shows not only the methodology and the results of model-based systems engineering to Automated Guided Transit(AGT) system as one of LMS systems, but also propose the extension of the model-based tool to help manage a project by linking WBS (Work Breakdown Structure), work organization, and PBS (Product Breakdown Structure). In performing the model-based functional analysis, the focus was on the operation concept of an example rail system at the top-level and the propulsion/braking function, a key function of the modern automated rail system. The model-based behavior analysis approach that applies a discrete-event simulation method facilitates the system functional definition and the test and verification activities. The first application of computer-aided tool, RDD-100, in the railway industry demonstrates the capability to model product design knowledge and decisions concerning key issues such as the rationale for architecting the top-level system. The model-based product design knowledge will be essential in integrating the follow-on life-cycle phase activities. production through operation and support, over the life of the AGT system. Additionally, when a new generation train system is required, the reuse of the model-based database can increase the system design productivity and effectiveness significantly.

• Journal of Korean Elementary Science Education
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• v.35 no.4
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• pp.416-425
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• 2016

As curriculum statements require addressing ethical and social issues which are raised by modern science and technology, the ability to perceive ethical and social issues regarding science is necessary for teachers to introduce socio-scientific issues (SSI) in their science class. The purpose of this study is to explore elementary school teachers' ethical sensitivity on SSI and attempts to give implications for teacher education. To explore the ethical sensitivity in the context of SSI, the revised version of the Test for Ethical Sensitivity on Science (TESS) was used. Two socio-scientific issues (genetic engineering and radioactive waste) were provided to read and write down five possible questions they believed should be considered before reaching a decision. Data was collected from eighty-two elementary school teachers in Korea. To analyze the ethical sensitivity, the responses including ethical considerations were analyzed by situation and ethical issues. The result showed that 81 out of 82 teacher participants provided at least more than one ethical consideration on each scenario of this study. However, not many teacher could raise various ethical issues and situation that ethical issue might occur. There were only a few teaches who could consider all the situations, 'process of scientific research', 'application of science and technology', and 'science influenced by society', that ethical issues might occur. Especially, teachers failed to consider that the ethical issue can occur in the situation when science is influenced by society. Based on the results, we suggest that during teacher education teachers need to experience finding various ethical issues that can occur in the context of SSI and especially considering the ethical issues when science is influenced by society.

• Journal of Advanced Navigation Technology
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• v.20 no.4
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• pp.314-320
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• 2016

Inertial navigation system (INS) has used aided systems and sensors to compensate navigation error. Global navigation satellite system (GNSS), velocity measurement sensor (VMS), and radar are commonly used to aid INS. Land navigation system (LNS) also mainly uses VMS when GNSS cannot be used such as at tunnel or on jammed scenario. A straight drive is required when VMS-aided navigation is used, because there is only speed of straight direction whereas no crossways and vertical directions. In local environment, even an expressway has lack of straight drive which is constraint of VMS-aided navigation algorithm. This paper proposes an enhanced VMS-aided navigation algorithm for LNS with indirect drive by restricting filter update condition. Also, there is a result of vehicle test to prove performance of the proposed algorithm.