• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2198-2202
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• 2005

In this paper we have presented a condition monitoring method of check valve using neural network. The acoustic emission sensor was used to acquire the condition signals of check valve in direct vessel injection (DVI) test loop. The acquired sensor signal pass through a signal conditioning which are consisted of steps; rejection of background noise, amplification, analogue to digital conversion, extract of feature points. The extracted feature points which represent the condition of check valve was utilized input values of fault diagnosis algorithms using pre-learned neural network. The fault diagnosis algorithm proceeds fault detection, fault isolation and fault identification within limited ranges. The developed algorithm enables timely diagnosis of failure of check valve’s degradation and service aging so that maintenance and replacement could be preformed prior to loss of the safety function. The overall process has been experimented and the results are given to show its effectiveness.

• 한국공간구조학회논문집
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• 제13권4호
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• pp.83-90
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• 2013

PTEF membranes are used for roofing materials of membrane structures. PTEF is the abbreviation of Poly-tetra Fluotide-ethylene. These materials are consisted of fiberglass weave and polyetrfluoroethylene coating. Also, PTEF membranes have some problems of structural capacity by wind or snow load, etc. In this study, sensor housings using lead switches are bonding in PTFE membranes, Monitoring to changes tension and tear damages are studied using radio frequency. If tension is received on edged membranes, bonded lead switches of sensor housings will be destroyed by changes tension, and these become to send signals of damages at the connected radio frequency system with increased tension. Study of these functional membrane materials will be contributed to prevent water leakage and long-term maintenance of membrane structures.

• Design & Manufacturing
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• 제16권4호
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• pp.52-59
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• 2022

Currently, Korea is an aging society and is expected to become a super-aged society in about four years. X-ray devices are widely used for early diagnosis in hospitals, and many X-ray technologies are being developed. The development of X-ray device technology is important, but it is also important to increase the reliability of the device through accurate data management. Sensor nodes such as temperature, voltage, and current of the diagnosis device may malfunction or transmit inaccurate data due to various causes such as failure or power outage. Therefore, in this study, the temperature, tube voltage, and tube current data related to each sensor and detection circuit of the diagnostic X-ray imaging device were measured and analyzed. Based on QC data, device failure prediction and diagnosis algorithms were designed and performed. The fault diagnosis algorithm can configure a simulator capable of setting user parameter values, displaying sensor output graphs, and displaying signs of sensor abnormalities, and can check the detection results when each sensor is operating normally and when the sensor is abnormal. It is judged that efficient device management and diagnosis is possible because it monitors abnormal data values (temperature, voltage, current) in real time and automatically diagnoses failures by feeding back the abnormal values detected at each stage. Although this algorithm cannot predict all failures related to temperature, voltage, and current of diagnostic X-ray imaging devices, it can detect temperature rise, bouncing values, device physical limits, input/output values, and radiation-related anomalies. exposure. If a value exceeding the maximum variation value of each data occurs, it is judged that it will be possible to check and respond in preparation for device failure. If a device's sensor fails, unexpected accidents may occur, increasing costs and risks, and regular maintenance cannot cope with all errors or failures. Therefore, since real-time maintenance through continuous data monitoring is possible, reliability improvement, maintenance cost reduction, and efficient management of equipment are expected to be possible.

• 한국구조물진단유지관리공학회 논문집
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• 제19권2호
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• pp.33-39
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• 2015

최근 급속한 기후변화 및 광범위한 사회간접시설의 개발 등으로 인해 사면붕괴가 곳곳에서 발생하고 있으며, 이에 대한 모니터링 및 예방시스템 구축에 대한 사회적인 관심이 증가하고 있는 상태이다. 사면붕괴 메카니즘에 영향을 미치는 중요한 영향인자는 지표내 수분 및 온도이며 이에 대한 변화 추이를 통해 사면붕괴를 예측할 수 있다. 따라서, 사면붕괴 모니터링을 위해서는 지표 깊이별 온도 및 함수비를 연속적으로 측정할 수 있는 복합센싱 기법이 필요하다고 볼 수 있다. 현재까지 온도 및 함수비에 대해 각각의 계측이 가능한 개별 센서는 다양하게 개발되어 있는 상태이지만, 온도 및 함수비를 동시에 연속적으로 측정할 수 있는 복합계측 시스템의 경우에는 많은 연구가 필요한 상태이다. 본 논문에서는 전류소모가 최소화된 측온 회로와 고주파 신호를 토양에 방사하는 수분 측정 센서를 적용한 고정밀 온도-함수비 복합센서를 개발하여 효율적이고 정확도를 향상시킨 사면붕괴 모니터링 시스템에 적용할 수 있도록 하였다. 개발된 복한센서의 성능검증을 위하여 기본성능 표준시험, 실내검증실험, 현장장기실험 등의 다양항 실험적 연구를 수행하였으며, 실험결과를 통해 개발된 복합센서를 이용한 모니터링 시스템은 지반의 온도 및 함수비를 정확하게 모니터링할 수 있는 것으로 나타났다.

• 한국CDE학회논문집
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• 제19권2호
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• pp.169-181
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• 2014

Recently ships and ocean platforms are becoming increasingly technological, unmanned, and huge. Maintenance and safety monitoring of these products is very important for safety reasons. Therefore, real-time monitoring of safety regions, such as the engine room, and hull structure, and environmental states, like fire and pressure of LNG tanks, is required for the sustainable ships. In this paper, a ZigBee-based wireless sensor network is suggested to monitor ships and ocean platforms effectively. However, this causes some telecommunication problems because these products are made of steel. To resolve this problem, we use the mesh networking of Zig-Bee that can monitor the regions and environmental states consistently. The telecommunication of such a monitoring system is tested on a real container ship and its performance is verified. The real-time monitoring results are displayed on the users' smart devices.

• Smart Structures and Systems
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• 제6권3호
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• pp.277-290
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• 2010

Internationally the load carrying capacity of bridges is decreasing due to material deterioration while at the same time increasing live loads mean that they are often exposed to stresses for which they were not designed. However there are limited resources available to ensure that these bridges are fit for purpose, meaning that new approaches to bridge maintenance are required that optimize both their service lives as well as maintenance costs. Wireless sensor networks (WSNs) provide a tool that could support such an optimized maintenance program. In many situations WSNs have advantages over conventional wired monitoring systems in terms of installation time and cost. In order to evaluate the potential of these systems two WSNs were installed starting in July 2007 on the Humber Bridge and on a nearby approach bridge. As part of a corrosion prevention strategy, a relative humidity and temperature monitoring system was installed in the north anchorage chambers of the main suspension bridge where the main cables of the bridge are anchored into the foundation. This system allows the Bridgemaster to check whether the maximum relative humidity threshold, above which corrosion of the steel wires might occur, is not crossed. A second WSN which monitors aspects of deterioration on a reinforced concrete bridge located on the approach to the main suspension bridge was also installed. Though both systems have provided useful data to the owners, there are still challenges that must be overcome in terms of monitoring corrosion of steel, measuring live loading and data management before WSNs can become an effective tool for bridge managers.

• Structural Monitoring and Maintenance
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• 제1권3호
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• pp.339-356
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• 2014

This study has been motivated to evaluate the practicality of numerical simulation of impedance monitoring for damage detection in steel column connection. In order to achieve the objective, the following approaches are implemented. Firstly, the theory of electro-mechanical (E/M) impedance responses and impedance-based damage monitoring method are outlined. Secondly, the feasibility of numerical simulation of impedance monitoring is verified for several pre-published experimental examples on steel beams, cracked aluminum beams, and aluminum round plates. Undamaged and damaged steel and aluminum beams are simulated to compare to experimental impedance responses. An aluminum round plate with PZT patch in center is simulated to investigate sensitive range of impedance responses. Finally, numerical simulation of the impedance-based damage monitoring is performed for a steel column connection in which connection bolts are damaged. From the numerical simulation test, the applicability of the impedance-based monitoring to the target steel column connection can be evaluated.

• 한국통신학회논문지
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• 제40권9호
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• pp.1808-1818
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• 2015

최근 신재생 에너지 중 각광을 받고 있는 풍력 발전의 경우 경제성 및 효율성을 높이기 위하여 대부분의 풍력 발전단지들이 해상에 조성된다. 그러나 풍력단지 관리자가 해상에 설치된 풍력발전기에 접근하기 위해서는 헬기 또는 보트를 이용해야하며 많은 비용과 시간을 필요로 한다. 이러한 유지 및 관리 비용을 감소시키기 위한 하나의 대안으로써 풍력발전기의 원격 모니터링 및 제어 기술이 요구된다. 본 논문에서는 풍력발전기의 상태 정보 계측 및 원격 제어 기능을 제공하는 무선 센서 네트워크 기반의 풍력발전기 모니터링 및 제어 시스템을 구현한다. 이를 위해 다수의 센서를 풍력발전기에 설치하여 실시간으로 상태를 계측할 수 있도록 하고 제어 장치를 통해 원격 제어가 가능하도록 한다. 풍력발전기의 센서 장치 및 제어 장치는 무선 센서 네트워크를 통해 제어 센터와 계측 데이터 및 제어 데이터를 주고받도록 한다. 제어 센터에서는 GUI 기반의 모니터링과 제어 기능을 제공하는 중앙 집중형 모니터링 프로그램을 통해 풍력발전기를 관리한다. 또한 제어 센터 이외의 지역에서 원격으로 풍력발전기 모니터링이 가능하도록 스마트 단말기 기반의 웹 프로그램을 구현한다.

• 비파괴검사학회지
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• 제35권6호
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• pp.421-428
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• 2015

An important trend in the sustainment of military aircraft is the transition from preventative maintenance to condition based maintenance (CBM). For CBM, it is essential that the actual system condition can be measured and the measured condition can be reliably extrapolated to a convenient moment in the future in order to facilitate the planning process while maintaining flight safety. Much research effort is currently being made for the development of technologies that enable CBM, including structural health monitoring (SHM) systems. Great progress has already been made in sensors, sensor networks, data acquisition, models and algorithms, data fusion/mining techniques, etc. However, the transition of these technologies into service is very slow. This is because business cases are difficult to define and the certification of the SHM systems is very challenging. This paper describes a possibility for fielding a SHM system on legacy military aircraft with a minimum amount of certification issues and with a good prospect of a positive return on investment. For appropriate areas in the airframe the application of SHM will reconcile the fail-safety and slow crack growth damage tolerance approaches that can be used for safeguarding the continuing airworthiness of these areas, combining the benefits of both approaches and eliminating the drawbacks.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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• pp.223-236
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• 1999

The need to monitor and undertake remidial works on large structures has greatly increased in recent years due to the appearance of widespread faults in large structures such as bridges and buildings, etc, of 20 or more years of age. The health condition of structures must be monitored continuously to maintenance the structures. In order to do in-situ monitoring, the sensor is necessary to be embedded in the structures. Fiber optic sensors can be embedded in the structures to get the health information in the structures. The fiber sensor was constructed with $3{\times}3$ fiber couplers to sense the multi-point strains and failure instants. The 4 RC (reinforced concrete) beams were made to 2 of A type, 2 of B type beams. These beams were reinforced by the reinforcing bars, and were tested under the flexural loading. The behavior of the beams was simultaneously measured by the fiber optic sensors, electrical strain gages, and LVDT. The states of the beams were interpreted by these all signals. By these experiments, There were verified that the fiber optic sensors could measure the structural strains and failure instants of the RC beams, The fiber sensors were well operated until the failure of the beams. It was shown that the strains of the reinforcing steel bar can be used to monitor the health condition of the beams through the flexural test of RC beams. On the other words, the results were arrived that the two strains in the reinforcing bar measured at the same point can give the information of the structural health status. Also, the failure instants of beams were well detected from the fiber optic filtered signals.