• Geomechanics and Engineering
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• v.12 no.4
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• pp.595-609
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• 2017

Due to high in-situ stress and brittleness of rock mass, the surrounding rock masses of underground caverns are prone to appear splitting failure. In this paper, a kind of loading-unloading variable elastic modulus model has been initially proposed and developed based on energy dissipation principle, and the stress state of elements has been determined by a splitting failure criterion. Then the underground caverns of Dagangshan hydropower station is analyzed using the above model. For comparing with the monitoring results, the entire process of rock splitting failure has been achieved through monitoring the splitting failure on side walls of large-scale caverns in Dagangshan via borehole TV, micro-meter and deformation resistivity instrument. It shows that the maximum depth of splitting area in the downstream sidewall of the main power house is approximately 14 m, which is close to the numerical results, about 12.5 m based on the energy dissipation model. As monitoring result, the calculation indicates that the key point displacement of caverns decreases firstly with the distance from main powerhouse downstream side wall rising, and then increases, because this area gets close to the side wall of main transformer house and another smaller splitting zone formed here. Therefore it is concluded that the energy dissipation model can preferably present deformation and fracture zones in engineering, and be very useful for similar projects.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.241-246
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• 2015

The interest of New Renewable Energy is increasing globally because of the increment of the uncertainty for the energy's supply and demand, and the increment of the frequency in weather anomaly and its damages. One of the New Renewable Energies, Hydrogen receives attention as the future energy that can deal with global environment regulation. Fuel Cell Electric Vehicle (FCEV) is an environment-friendly vehicle that uses Hydrogen as fuel. The electric power for FCEV is generated by chemical reaction with Oxygen from the air and Hydrogen. Hyundai Motor Company (HMC) has developed a proprietary fuel cell system since 2005. In 2012, HMC is the first car maker that mass-produces the ix35 FCEV to the worldwide such as North America, Europe, etc. In order to develop and improve the FCEV technology, data acquisition and analysis of the driving vehicle information is essential. Therefore, the monitoring system is developed, which is consist of datalogger, Automatic Vehicle Location (AVL) server and main server. Especially, WCDMA technology is integrated into the system which enables the data analysis without any restriction of time and region. The main function of the system is the analysis of the driving pattern and the component durability, and the safety monitoring. As a result, ix35 FCEV has successfully developed by using the developed monitoring system. The system is going to take an advantage of development in the future FCEV technology.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.92-97
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• 2005

The $9 billion US global wind energy market is experiencing dramatic growth with installed generating capacity up 500% from 7,600 MW at the end of 1997 to nearly 39,300 MW at the end of 2003. With an average annual increase approaching 32%, wind is the world's fastest growing energy source on a percentage basis, and its growth is forecast to continue a double-digit pace into the next decade 1. While much of this growth is fueled by government decisions that are favorable to 'green' or renewable Power, it is also fueled by advances in wind turbine technology as evidenced by larger, more sophisticated machines. As a result, wind turbines are becoming more established as an economically viable alternative to fossil-fueled power generation. Today, wind 'farms' - consisting of anywhere from a single turbine to as many as several hundred turbines - are an important component of the world's source of electric energy.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1661-1667
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• 2011

This study was intended to identify the applicability of energy harvesting technologies for powering a wireless health monitoring sensor system of railroad vehicle. As measuring surrounding energy under the normal operation environment, it is possible to predict amount of the applicable energy. The results of energy prediction represents the feasibility of power sources for wireless sensor systems through energy harvesting technologies under the circumstance in which the thermal energy and vibration energy are generated.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.147-149
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• 2015

ECDIS(전자해도표시장치) 기반에 선박의 연료 효율성 모니터링 시스템인 SEEMS(Ship Energy Efficiency Monitoring System)를 연계하여 표시하고, 해상 기상 예보 정보를 도식화 하는 방법에 관하여 연구하였다.

• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.293-302
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• 2020

Food safety has emerged as a growing concern for human health in recent times. Consuming contaminated food may lead to serious health problems, and therefore, a system for monitoring food freshness that is both non-detrimental to the quality of food and highly accurate is required to ensure that only high-quality fresh food packages are provided to the customers. This paper proposes a method to monitor and detect food quality using a compact smart sensor tag. The smart tag is composed of three ultra-low-power sensors, which monitor four major indicators of food freshness: temperature, humidity, and the concentrations of ammonia and hydrogen sulfide gases. An RF energy scavenging circuit is integrated into the smart sensor tag to harvest energy from radio waves at a high frequency of 13.56 MHz to supply sufficient power to the tag. Experimental results show that the proposed energy harvester can efficiently obtain energy at a distance of approximately 40 cm from a 4 W reader. In addition, the proposed smart sensor tag can operate without any battery, thereby eliminating the requirement of frequent battery replacement and consequently decreasing the cost. Meanwhile, the freshness of preserved pork is continuously monitored under two conditions--room temperature and refrigerator temperature--both of which are the most common temperatures under which food is generally stored. The food-monitoring experiments are conducted over a period of one week using the proposed battery-less tag. Based on the experimental results, the food assessment is classified into four categories: fresh, normal, low, and spoiled.

• Smart Structures and Systems
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• v.22 no.2
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• pp.231-237
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• 2018

A significant data problem is encountered with condition monitoring because the sensors need to measure vibration data at a continuous and sometimes high sampling rate. In this study, compressive sensing approaches for condition monitoring are proposed to demonstrate their efficiency in handling a large amount of data and to improve the damage detection capability of the current condition monitoring process. Compressive sensing is a novel sensing/sampling paradigm that takes much fewer data than traditional data sampling methods. This sensing paradigm is applied to condition monitoring with an improved machine learning algorithm in this study. For the experiments, a built-in rotating system was used, and all data were compressively sampled to obtain compressed data. The optimal signal features were then selected without the signal reconstruction process. For damage classification, we used the Variance Considered Machine, utilizing only the compressed data. The experimental results show that the proposed compressive sensing method could effectively improve the data processing speed and the accuracy of condition monitoring of rotating systems.

• Smart Structures and Systems
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• v.6 no.3
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• pp.263-275
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• 2010

In the last decade, wireless sensor networks have emerged as a promising technology that could accelerate progress in the field of structural monitoring. The main advantages of wireless sensor networks compared to conventional monitoring technologies are fast deployment, small interference with the surroundings, self-organization, flexibility and scalability. These features could enable mass application of monitoring systems, even on smaller structures. However, since wireless sensor network nodes are battery powered and data communication is the most energy consuming task, transferring all the acquired raw data through the network would dramatically limit system lifetime. Hence, data reduction has to be achieved at the node level in order to meet the system lifetime requirements of real life applications. The objective of this paper is to discuss some general aspects of data processing and management in monitoring systems based on wireless sensor networks, to present a prototype monitoring system for civil engineering structures, and to illustrate long-term field test results.

• 한국IT서비스학회:학술대회논문집
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• 2010.05a
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• pp.151-154
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• 2010

In this paper, we propose an energy monitoring and management service based on wireless sensors and a home gateway for homes and buildings. Homes and buildings have a significant energy saving potential compared with other sectors. Sensing, monitoring, and managing of the information on the energy consumption are required for an efficient energy saving service. The proposed system is composed of two main components, wireless sensor and an intelligent home gateway. Wireless sensors have the ZigBee communication interface for communication, and the intelligent home gateway is an energy portal. We expect that energy saving could be achieved with this system. As a further work, we will analyze the practical impact of the proposed service.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.32-48
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• 2018

Monitoring of energy use should be a priority in order to efficiently manage building energy use. Energy use in buildings can be managed by dividing them into energy sources, uses, and ZONE. By energy source, electricity, gas, fuel, and district heating are supplied to run the building's facilities. The purpose can be divided into five main applications, including cooling, heating, lighting, hot water and ventilation, but not many elevators and electric heaters that are difficult to include in the five applications are classified. ZONE Star refers to the comparison or separate management of areas for which the purpose of the building is similar or different. In addition, energy efficiency management requires control of the temperature, humidity, and people who will be measuring energy in the building, and the recent problem of fine dust should directly affect the ventilation of the building.