• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.1-8
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• 2016

Recently, buildings tend to be large size, complex shape and functional. As the size of buildings is becoming massive, the need for structural health monitoring(SHM) technique is ever-increasing. Various SHM techniques have been studied for buildings which have different dynamic characteristics and are influenced by various external loads. Generally, the visual inspection and non-destructive test for an accessible point of structures are performed by experts. But nowadays, the system is required which is online measurement and detect risk elements automatically without blind spots on structures. In this study, in order to consider the response of non-linear structures, proposed a signal feature extraction and the adaptive threshold setting algorithm utilized to determine the abnormal behavior by using statistical methods such as control chart, root mean square deviation, generalized extremely distribution. And the performance of that was validated by using the acceleration response of structures during earthquakes measuring system of forced vibration tests and actual operation.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.141.2-141.2
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• 2015

교류임피던스 측정기법을 이용하여 전기화학적으로 외부환경에서 소재 금속까지 물질 및 전하이동에 관한 임피던스 측정이 가능하며 도막의 부식 및 노화정도 및 내식성의 평가가 가능하여 산업체에서 널리 이용되고 있다. RPCS(Remote Plasma Cleaning Source)는 패널 및 반도체 제조공정에서 CVD 증착공정 후 챔버 내부에 입혀지는 Si(실리콘)을 화학적으로 세정하기 위한 F(불소) Radical을 공급하는 원격 고밀도 플라즈마를 발생시키는 제품이다. RPCS의 바디는 알루미늄을 사용하고 절연 및 플라즈마에 대한 내구성을 확보하기 위해 아노다이징 코팅을 한다. 반응기 내벽의 표면이 공정 플라즈마에 노출될 때 소재는 화학적으로 매우 활성이 높은 라디칼과의 반응뿐만 아니라 이온의 충격을 동시에 받게 되며 이 과정에서 다량의 불소 (Fluorine) 라디칼과 전계에 반응한 이온의 운동에 노출되면서 아노다이징 코팅이 손상되는데 이는 기기의 수명 단축 및 파티클을 발생시키며, Arc의 원인이 되기도 한다. 실제 사용 환경에서는 기기의 분해 없이 아노다이징의 상태를 주기적으로 모니터링 하기가 대단히 어려워, 정기적으로 교체하고 있는 실정이다. 본 연구에서는 RPCS내 발생된 플라즈마 현상을 컨덕터로 활용하여 고주파 리액턴스를 임피던스로 환산하여 아노다이징 코팅의 손상 정도를 진단 및 모니터링하였다. 아노다이징이 손상된 내부 블럭과 정상상태인 내부 블럭의 임피던스를 비교하였고, 아노다이징 두께별 임피던스를 측정하였다. 그 결과 아노다이징 절연막이 손상된 블록의 임피던스가 정상 블록에 비해 낮았으며 두께별 임피던스도 비례함을 알 수 있었다. 향후에는 장기간 현장에서 축척되어진 시험데이터를 바탕으로 아노다이징 코팅의 수명예측진단 시스템을 구축하고자 한다.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.6
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• pp.691-697
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• 2006

Induction motors are critical components in industrial process. So there are many research in the condition based maintenance, online monitoring system, and fault detection. This paper presents a scheme on the detection and diagnosis of the three-phase squirrel induction motor under unbalanced voltage, broken rotor bar, and a combination of these two faults. Actually one fault happen in operation, it influence other component in motor or cause another faults. Accordingly it is useful to diagnose and detect a combination fault in induction motor as well as each fault. The proposed fault detection and diagnosis algorithm is based on the stator currents from the squirrel induction motor and simulated with the aid of Matlab Simulink.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.469-472
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• 2007

The telemedicine system provide an efficient means to monitor the status of health and measure bio-information even though the limitation of distance and time. The telemedicine system can be divided into two categories. The first one is Remote Support Service which can monitor the patient including home environments and give those diagnosis information to medical office. and the other one is Alarm Service that can be used for tile emergency status. For the convenience of the patient we will design and implement portable healthcare device and the telemedicine system under the wireless ZigBee network environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.136-143
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• 2013

In this paper, a monitoring system for telecommunication tower using wireless sensor network is presented. Although safety inspection could be judged by eyesight and calculating original design from now, not only this system can protect perils, estimating data exactly, but also it is effective to management. It is also economic because the system costs cheaper expenses for telecommunication tower of setting it once than for the tower of inspecting its safety regularly. This paper proves that the structure can be managed scientifically and efficiently, and the system contributes not only stabilized telecommunication services for users but reducing damages.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.4
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• pp.351-359
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• 2011

In a structure, damage can occur at several scales from micro-cracking to corrosion or loose bolts. This makes the identification of damage difficult with one mode of sensing. Hence, a multi-mode actuated sensing system is proposed based on a self-sensing circuit using a piezoelectric sensor. In the self sensing-based multi-mode actuated sensing, one mode provides a wide frequency-band structural response from the self-sensed impedance measurement and the other mode provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. In this study, an experimental study on the pipeline system is carried out to verify the effectiveness and the robustness of the proposed structural health monitoring approach. Different types of structural damage are artificially inflicted on the pipeline system. To classify the multiple types of structural damage, a supervised learning-based statistical pattern recognition is implemented by composing a two-dimensional space using the damage indices extracted from the impedance and guided wave features. For more systematic damage classification, several control parameters to determine an optimal decision boundary for the supervised learning-based pattern recognition are optimized. Finally, further research issues will be discussed for real-world implementation of the proposed approach.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1783-1785
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• 2012

도시재생의 효율적인 정책수립 및 사업추진을 위해서는 여러 분야에서 제공되고 있는 다양한 정보 DB들을 연계하여 체계화된 도시재생 관련 정보를 제공할 수 종합정인 정보제공 시스템이 필요하다. 본 연구에서는 도시쇠퇴의 진단을 바탕으로 재생 필요지역 추출, 지표 모니터링, 평가 등을 수행할 수 있는 시스템을 설계하였다. 또한 관련 정보의 효율적인 유통 및 정보 피드백을 통해 도시재생 정보를 효율적으로 제공할 수 있는 정보공유 포털 구축방안을 제시하고자 한다.

• Journal of the Institute of Convergence Signal Processing
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• v.23 no.2
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• pp.84-90
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• 2022

Machine tool state monitoring is a process that automatically detects the states of machine. In the manufacturing process, the efficiency of machining and the quality of the product are affected by the condition of the tool. Wear and broken tools can cause more serious problems in process performance and lower product quality. Therefore, it is necessary to develop a system to prevent tool wear and damage during the process so that the tool can be replaced in a timely manner. This paper proposes a method for diagnosing five tool states using a deep learning-based hierarchical convolutional neural network to change tools at the right time. The one-dimensional acoustic signal generated when the machine cuts the workpiece is converted into a frequency-based power spectral density two-dimensional image and use as an input for a convolutional neural network. The learning model diagnoses five tool states through three hierarchical steps. The proposed method showed high accuracy compared to the conventional method. In addition, it will be able to be utilized in a smart factory fault diagnosis system that can monitor various machine tools through real-time connecting.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.135-144
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• 2009

The cable system of suspension bridges is a very important non-elastic element which caries an external load by a tension force of the cable, such that creates the integrity of a structure. It is not easy to find if cable system have been changed by the maintenance activities such as repairs or reinforcement. Sometimes the maintenance can cause structural deformations and changes of the tension force in cables. In most cases, the cable stayed bridges are managed by health monitering system, however, the main cable of suspension bridges need to develop more accurate and efficient monitoring system. The Namhee Bridge was constructed 35 years ago and it has been continually repaired and reinforced after then. This study describes the behavior of the cable system by analysing many of inspective reports and by using the results of hanger rope test and for the shape of main cables surveys.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.12
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• pp.1397-1404
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• 2014

Grab cranes are used for multi-purpose when the sand and soil are deposited into harbor wharf or the undersea construction is performed. Among the components of crane grab, the wire drum and disc brake pad are key expendables and have disadvantages that lot of heat is generated and very expensive when replacing them. In this study, the thermal image analysis for the disc brake, which works with wire drum of the crane is suggested. The suggested system performs the pad thermal diagnosis through the thermal image using the characteristics that the disc and pad surface temperatures are distributed abnormally before the brake failure and the disc pad damage. Therefore, the damage by the failure can be prevented by discovering the abnormality of the machine parts before failure and the life cycle of the pad and the cost can be extended and saved by operating the crane performing constant checkup for the overload.