• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.939-949
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• 2017

Prognostics and health management(PHM) is actively utilized by industry as an essential technology focusing on accurately monitoring the health state of a system and predicting the remaining useful life(RUL). An effective PHM is expected to reduce maintenance costs as well as improve safety of system by preventing failure in advance. With these advantages, PHM can be applied to the battery system which is a core element to provide electricity for devices with mobility, since battery faults could lead to operational downtime, performance degradation, and even catastrophic loss of human life by unexpected explosion due to non-linear characteristics of battery. In this paper we mainly review a recent progress on various models for predicting RUL of battery with high accuracy satisfying the given confidence interval level. Moreover, performance evaluation metrics for battery prognostics are presented in detail to show the strength of these metrics compared to the traditional ones used in the existing forecasting applications.

• Journal of Veterinary Clinics
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• v.20 no.3
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• pp.369-375
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• 2003

The ultrasonography was performed in 77,924 subestrous dairy cows from 680 dairy farms at 57 districts. The cows were examined for confirmation of resumption of ovaries and uterus after 30 days postpartum, for early pregnancy diagnosis after 30 days post-insemination, confirmation of pregnancy at 8 month post-insemination, and for diagnosis of reproductive dysfunctions, respectively. The results of reproductive examination by ultrasonography in 77,924 dairy cows were ovarian disorders 35,452 (46.8%), uterine disorders 10,721 (13.8%), pregnancy and pregnant failure 24,044 (30.8%), adhesion of reproductive tracts 167 (0.2%), freematins 13 (0.01%) and others 6,527 (8.4%) cows, respectively. The 13,732 (49.6%) cows out of 27,694 cows were treated for silent heat or error of estrus detection, 3,473 (12.5%) cows for follicular cysts, 815 (3.0%) cows for luteal cysts, 606 (2.2%) cows for inactive ovaries, 4 (0.01%) cows for granulosa cell tumors, and 6,455 (23.3%) cows for endometritis, respectively. The indices of reproductive efficiencies before (2001-08-10) and after (2003-07-20) periodical examination of reproductive status were as follows; the mean intercalving interval were shortened from 471 days to 383 days, the mean interval calving to conception were shortened from 187 days to 99 days, the mean interval calving to first service were shortened from 105 days to 67 days, the mean cows showing heat by 60 days postpartum were increased from 33% to 89%, the mean conception rate to first service were increased from 43% to 68%, and the mean service per conception were shortened from 2.6 times to 1.8 times, respectively. These results suggest that periodical examination of reproductive status would be useful for the improvement of the reproductive performance in dairy cows.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.782-795
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• 2019

Safety is always acritical focus of exploration of ocean resources, and it is well recognized that human factor is one of the major causes of accidents and breakdowns. Our research developed a dynamic human reliability assessment approach, Predicted Mean Vote-Cognitive Reliability and Error Analysis Method (PMV-CREAM), that is applicable to monitoring the cognitive reliability of oceanauts during deep-sea missions. Taking into account the difficult and variable operating environment of manned submersibles, this paper analyzed the cognitive actions of oceanauts during the various procedures required by deep-sea missions, and calculated the PMV index using human factors and dynamic environmental data. The Cognitive Failure Probabilities (CFP) were calculated using the extended CREAM approach. Finally, the CFP were corrected using the PMV index. This PMV-CREAM hybrid model can be utilized to avoid human error in deep-sea research, thereby preventing injury and loss of life during undersea work. This paper verified the method with "Jiaolong" manned submersible 7,000 m dive test. The"Jiaolong" oceanauts CR(Corrected CFP) is dynamic from 3.0615E-3 to 4.2948E-3, the CR caused by the environment is 1.2333E-3. The result shown the PMV-CREAM method could describe the dynamic human reliability of manned submersible caused by thermal environment.

• Spatial Information Research
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• v.17 no.4
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• pp.405-416
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• 2009

According to the changes of the city's paradigm, the demand on u-City increases rapidly. u-City has been built at 54 areas in Korea (as of May 2009). One of the important determinants of success or failure in the increasing of u-City is how to provide u-Services. Most current u-Services are Sensor Network-based monitoring services to manage urban infrastructure. u-GIS is one of fundamental requirements to implement 'any time and any where' u-Service which covers the essential meaningful term "ubiquitous". Hence, in this paper, we 1) describe the definition of the spatial awareness, 2) discuss how to converge (Spatial Embedding) among different spatial data : topographic spatial data, sensor spatial data, and more, 3) bring forth an advanced form of u-Service, 4) analyze the state-of-the-art u-GIS techniques.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.454-461
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• 2003

This study addressed a procedure to carry out an experimental study on a behavior of simple and continuous concrete beams. For this purpose, sample concrete beams were fabricated and sensors for the measurement of strains and deflections were attached both on the surface of the beams and inside them. Two types of sensors were used to measure strains associated with loading: electric resistance strain sensors and fiber optic sensors. Displacement gauges were also attached on the bottoms of beams to investigate the behavior of beams more rationally. The behavior of the beams was then evaluated throughout the results measured from different sensors while they were subject to steady loading up to failure. From results of this study, it was found that concurrent use of sensors and displacement gauges is helpful in investigating the behavior of concrete beams more effectively. Especially, combined-type strain sensors specifically fabricated in this experiment were found not to be affected by the occurrence of cracks so significantly and to be very effective in monitoring strains of concrete structure. It was also observed that beams show nonlinear force-displacement relationship and reinforcing bars take charge of resisting the external force once cracks occur in concrete beams.

• 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.

• Journal of Biomedical Engineering Research
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• v.35 no.5
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• pp.119-124
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• 2014

A Ventricular assist device (VAD) is one of the most efficient treatments to raise the survivability of the end stage heart failure patient. However, some of LVAD patients have died for the failures and improper control of LVAD. To detect critical dangers in LVAD, the monitoring methods of LVAD outflow have been requested, because it can be affected by patient's hemodynamic states and abnormal conditions of LVAD. In the case of an external pulsatile LVAD, the air movement through the air line can be used to estimate LVAD outflow. In this study, the air movement in the air-line of the extracorporeal pulsatile LVAD was measured with a differential pressure sensor between different points. The precise estimation of air movement could be achieved by additional measurement of air pressure. In a series of in-vitro experiments, the LVAD outflow were changed according to the afterload of LVAD and the differential pressure of LVAD didn't have close correlation with the LVAD outflow that were measured with an ultrasonic flowmeter at the same time. However, new precise estimation with the data from differential pressure and one point pressure in the air-line showed higher correlations with LVAD outflow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.90-96
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• 2020

In this era, intelligence is considered a major factor in the defense sector. As a result, securing technology for weapons systems for monitoring and reconnaissance of companies has become inevitable. As a result, UAVs (Unmanned Aerial Vehicles) have been developed and are actively operating around the world if the flight operation of manned aircraft is restricted, such as in environments that are too dangerous, messy or boring for the military to perform directly. The system of unmanned aerial vehicles, which has been researched and developed in Korea, includes Air Vehicle Test Equipment(AVTE). AVTE is equipment that is connected to an UAV to check its status and allows the operator to check its flightability by issuing an operational command to the UAV and verifying that it follows the command values. This study conducts fault finding on the phenomenon where the AVTE has stopped operating due to engine noise during these operations and analyzes the cause in terms of software, hardware and external environment. Present improvement measures according to the cause are analyzed and the results of verifying that the proposed measures can prevent failure are addressed.

• Journal of Navigation and Port Research
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• v.41 no.5
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• pp.277-286
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• 2017

IMO introduced e-Navigation concept to improve the efficiency of ship operation, port operation, and ship navigation technology. IMO proposed sixteen MSPs (Maritime Service Portfolio) applicable to the ships and onshore in case of e-Navigation implementation. In order to meet the demands of the international society, the system implementation work for the Korean e-Navigation has been specified. The Korean e-Navigation system has five service categories: the S2 service category, which is a ship anomaly monitoring service, is a service that classifies emergency levels according to the degree of abnormal condition when a ship has an abnormality in ship operation, and provides guidance for emergency situations. The navigation safety module is a sub-module of the S2 service that determines the emergency level in case of navigation equipment malfunctioning, engine or steering gear failure during navigation. It provides emergency response guidance based on emergency level to the abnormal ship. If an abnormal condition occurs during the ship operation, first, the ship shall determine the emergency level, according to the degree of abnormality of the ship. Second, an emergency response guidance is generated based on the determined emergency level, and the guidance is transmitted to the ship, which helps the navigators prevent accidents and not to spread. In this study, the operational concept for the implementation of the Korean e-Navigation system is designed and the concept is focused on the navigation safety module of S2 service.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.414-416
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• 2003

As environmental conditions for memory products are increasingly high speed/high density, adopting diverse system configuration, it's more and more difficult for current component tester to adopt the actual condition of field application. If system test screening is realized in component level, test coverage failure can be made more secured in the initial stage, evaluation cost can be reduced and the effectiveness of investment for the facility can be maximized. Based on the above background, component automatic system tester was developed and showed off satisfactory results per each memory device family. In this paper, component quality stabilization strategy and cost saving for tester investment through future Quality monitoring and application to mass production will be presented.