• Journal of Institute of Control, Robotics and Systems
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• v.15 no.12
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• pp.1246-1253
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• 2009

To be high efficient for a navigation of unmanned ground vehicle, it must be able to distinguish between safe and hazardous regions in its immediate environment. We present an advanced method using laser range finder for building global 2D digital maps that include environment information. Laser range finder is used for mapping of obstacles and driving environment in the 2D laser plane. Rotary encoders are used for localization of UGV. The main contributions of this research are the development of an algorithm for global 2D map building and it will turn a UGV navigation based on map matching into a possibility. In this paper, a map building algorithm will be introduced and an assessment of algorithm reliability is judged at an each environment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.378-381
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• 2003

Efficient development of method on a performance evaluation for machine tools has been regarded as the most important work for accuracy and quality enhancement to every user and manufacturer. A evaluation method of accuracy for machine tools has been studied recently according to the rapid increase of interest in precision machine tools. To this point of view, the circular interpolation test of machine tools is recognized as the most useful method to distinguish a dynamic accuracy of NC machine tools by ISO and ANSI/ASME, etc. In this paper, we have studied and developed the form measurement system with grid encoder to analyse the final accuracy of NC machine tools. we have analyzed the servo system error and geometric error of NC machine tools through measuring a dynamic error signal by this system. and then we verified the experimental result and enhanced the reliability by means of comparing the characteristics of the developed system with the kinematic ball-bar system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.44-45
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• 2008

The zone 3 elements of distance relays play an important role during the propagation of cascaded events. The most challenging problem to mitigate catastrophic failures is to distinguish between actual faults with line flow transfer from other disconnected lines. This paper presents an adaptive protective relaying scheme based on Line Outage Distribution Factor(LODF) and Generation Shift Factor(GSF) to prevent zone 3 tripping during the cascaded events. Internet based secure peer to peer communication is recommended as a communication method of proposed scheme. Several communication issues such as reliability, speed and cyber security are discussed. In order to establish the feasibility of the proposed scheme, computer simulations for a six bus system has been performed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1634-1640
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• 2017

The study aims to distinguish hemiplegic gait and normal gait using simple wearable device and classification algorithm. Thus, we developed a wearable system equipped three axis accelerometer and three axis gyroscope. The developed wearable system was verified by clinical experiment. In experiment, twenty one normal subjects and twenty one patients undergoing stroke treatment were participated. Based on the measured inertial signal, a random forest algorithm was used to classify hemiplegic gait. Four-fold cross validation was applied to ensure the reliability of the results. To select optimal attributes, we applied the forward search algorithm with 10 times of repetition, then selected five most frequently attributes were chosen as a final attribute. The results of this study showed that 95.2% of accuracy in hemiplegic gait and normal gait classification and 77.4% of accuracy in hemiplegic-side and normal gait classification.

• Journal of Korean Society of Water and Wastewater
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• v.38 no.2
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• pp.83-93
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• 2024

In this study, we present a sewer pipe inspection technique through a combination of active sonar technology and deep learning algorithms. It is difficult to inspect pipes containing water using conventional CCTV inspection methods, and there are various limitations, so a new approach is needed. In this paper, we introduce a inspection method using active sonar, and apply an auto encoder deep learning model to process sonar data to distinguish between normal and abnormal pipelines. This model underwent training on sonar data from a controlled environment under the assumption of normal pipeline conditions and utilized anomaly detection techniques to identify deviations from established standards. This approach presents a new perspective in pipeline inspection, promising to reduce the time and resources required for sewer system management and to enhance the reliability of pipeline inspections.

• Journal of Korea Water Resources Association
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• v.49 no.5
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• pp.381-389
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• 2016

In this study, we developed evaluation indicators of dam rehabilitation considering climate change in order to prepare for safety of aging dam facilities in accordance with changes in rainfall intensity. The validity and appropriateness of each indicator, and the evaluation criteria were selected for quantitative indicators for each detail through domestic and international case studies, literature review, and expert advice. The survey was carried out to estimate the importance of each indicator for dam rehabilitation. The subjective assessment of the respondents was rearranged using pairwise comparison from the Analytic Hierarchy Process (AHP). The reliability of the survey results was evaluated through consistent verification. In addition, a comparative assessment was carried out which evaluated the reliability importance estimation result to refine the criteria to distinguish rating scales between expert and non-expert groups on dam-related fields.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.291-293
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• 2017

Security services that support electric energy service gateway require relatively high reliability. In particular, the application services that accompany communications and data are run organically. Each of the security services should support a secure service platform that supports a secure, scalable life cycle for existing services which should be extends security layer of Universal Middleware such as OSGi platform. In this convergence platform, it is the study of security transfer modular services that allow independent life cycle management of systems through Universal middleware. First, It is modular in terms of energy consumption service and data, enabling real-time operation, communications, remote management and applications. Second, the life cycle of the secure module to support the life cycle of secure, delete, start and updating of the security module by applying the security policy module layer concept. It is modular in terms of power generation and accountability, enabling us to distinguish between reliability and accountability in a large volume of data models in the smart grid, the service was intended to be standardized and applied to the security service platform.

• Journal of Korean Clinical Health Science
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• v.8 no.2
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• pp.1426-1435
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• 2020

Objective: This study aims to develop CFT, a screening test for dementia that can be conducted on patients with mild cognitive impairment or early dementia. Methods: This study was conducted on therapists working at occupational therapy hospital in Gyeongsangnam-do. The data collection period is two months from July to September 2020, and the research participants were briefed on the purpose, significance, and anonymity of the research in consideration of ethical issues. A total of 33 copies of the data were finally analyzed, excluding those containing insufficient answers and errors, by distributing 40 copies of the data. SPSS Data Access pack 8.0 was used for data analysis, Cronbach's α value was evaluated for internal consistency reliability of each item, and Pearson Correlation coeffient between the lower scales of the assessment tool was measured. Results: The Cronbach's α value of the CFT was shown as .892 and the reliability of the assessment paper was shown to be quite high. The Cronbach's α value for each item in the cognitive assessment tool was the highest at .899 in the subtraction item, with exercise control (mook Chi Pa) at 888, visual memory, plus .887. The correlation of each item of cognitive assessment tools was found to be most correlated with the number of sustained concentrates and word2 to .934; in the stop word-numeric item and visual memory to be .85; and in the addition to the auditory memory item .739. Conclusion: Therefore, this study developed cognitive evaluation tools that can distinguish the diversity and cognitive level of screening tests and clarify standards, which are different from the existing dementia screening tools in Korea. Furthermore, the cognitive assessment tools of this study can be verified by applying them to patients with mild cognitive impairment and early dementia, and the criteria for generalization can be established.

• Journal of the Korea Society of Computer and Information
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• v.28 no.3
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• pp.149-157
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• 2023

The purpose of this study is to suggest that performers in the performing arts actively utilize the loading dock and stage door when evacuating from the stage space of a performance hall in a crisis situation. Therefore, first, we analyzed the system related to the performance hall's safety. The stage evacuation type was classified into A, B, C, and D forms by applying the building law audience evacuation standards. Second, statistical data were organized based on measurement data, and the characteristics of each form were summarized. Third, the network reliability measurement method was borrowed to evaluate the evacuation safety of the evacuation route in the stage space. We confirmed quantitatively that the direction of the loading dock direction and stage door direction on the stage is advantageous for evacuation. In this study, it was possible to distinguish the advantage of evacuation according to the type of evacuation, (A(0.1274)>B(0.1228).>.C(0.0487)) with A being the most advantageous. These results can be expected to improve the evacuation safety of the stage, and furthermore, they are expected to be used as basic data for stage evacuation.

• Korean Journal of Materials Research
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• v.20 no.6
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• pp.307-311
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• 2010

Positron annihilation lifetime spectroscopy is applied to BaSrFBr : Eu film which is used for the phosphore layer, and afterwards the reliability and self-consistency of source corrections in the positron lifetime spectroscopy is investigated using a $^{22}Na$ positron emitter covered by thin foils. The positron lifetime showed no significant change through the various proton irradiation energies. It is unusual that the measurements of the defects indicate that most of the defects were likely to have been generated by X-ray radiation. This may have resulted from the Bragg peaks of the proton characteristics. The Bragg peak does not affect the defect signals enough to distinguish the lifetimes and intensities in a material that is includes multi-grains. The lifetime ($\tau_1$) associated with positron annihilations in the Ba, Br, and Eu of the sample was about 250 ps, and due to the annihilations at F-centers or defects from the irradiated protons in sample, the lifetime ($\tau_2$) was about 500 ps.