• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.915-916
• /
• 2006

본 논문은 원자력 발전소의 금속파편감시계통(LPMS)에서 충격신호의 탐지를 위해 사용되는 하드웨어 구현에 관한 것이다. 본 논문에서 구현한 것은 LPMS의 하드웨어 중에서 입력된 신호를 디지털로 변환하여 충격신호의 트리거 판단기능을 하는 DAM(Data acquisition module)보드이다. 본 논문에서 구현한 DAM은 디지털 필터와 트리거 판단을 위한 알고리즘이 DSP에서 실시간으로 처리되어 LPMS의 기능을 업그레이드 하였다.

• Journal of the Korea Convergence Society
• /
• v.9 no.7
• /
• pp.9-16
• /
• 2018

The purpose of this study is to prevent the malicious user from breaking the door-lock due to physical impact. If it matches the analog displacement value set in the door-lock system, it protects the body and property by transmitting damage information in real time to the manager smart phone. The research suggests a system that transmits damage information in real time to registered users when door-lock is damaged by physical impact. Then compare the impact information sensed by the door lock with the data of the sensitivity control unit. In the web server of the proposed system, after impact information transmitted from Door-Lock is stored in the DB, if the impact information is larger than the shock detection transmission reference value stored in the DB, it is transmitted to the administrator in real time by SMS module so that illegal access information.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.32 no.1
• /
• pp.47-55
• /
• 2012

A structural health monitoring technique for locating impact position in a plate structure is presented in this paper. The method employs a single sensor and spatial focusing of time reversal (TR) acoustics. We first examine the TR focusing effect at the impact position and its surroundings through simulation and experiment. The imaging results of impact points show that the impact source location can be accurately estimated in any position of the plate. Compared to existing techniques for locating impact or acoustic emission source, the proposed method has the benefits of using a single sensor and not requiring material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in other ultrasonic testings of plate-like structures.

• Composites Research
• /
• v.24 no.6
• /
• pp.49-55
• /
• 2011

The use of advanced composite materials in main structures of military and civil aircraft has been increased rapidly because of their considerable metals in high specific strength and stiffness. However, the mechanical properties of composite materials may severely degrade in the presence of damage. Especially, the high-velocity impact such as a hailstorm, and a small piece of tire or stone during high taxing, can cause considerable damage to the structures and sub-system in spite of a very small mass. However, it is not easy to detect the damage in composite plates using a single sensor or any conventional methods. In this paper, the PVDF sensors and AE sensors were used for monitoring high-velocity impact damage initiation and propagation in composite laminates. The WT(wavelet transform) is used to decompose the sensor signals. In the PVDF sensor and AE sensor signal analysis, amounts of high-frequency signals are increased when the impact energy is increased. PVDF sensor and AE sensor signal appeared similar results. This study shows how various sensing techniques can be used to characterize high-velocity impact damage of advanced composite laminates.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.36 no.5
• /
• pp.391-398
• /
• 2016

Acoustic emission (AE) is one of the most powerful techniques for detecting damages and identify damage location during operations. However, in case of the source location technique, there is some limitation in conventional AE technology, because it strongly depends on wave speed in the corresponding structures having heterogeneous composite materials. A compressed natural gas(CNG) pressure vessel is usually made of carbon fiber composite outside of vessel for the purpose of strengthening. In this type of composite material, locating impact damage sources exactly using conventional time arrival method is difficult. To overcome this limitation, this study applied the previously developed Contour D/B map technique to four types of CNG storage tanks to identify the source location of damages caused by external shock. The results of the identification of the source location for different types were compared.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.6
• /
• pp.659-666
• /
• 2015

In this paper, various influence factors on the impact-echo test which is an effective method in characterizing defects such as such as the delamination in the concrete structures were studied. The side to thickness ratio(a/h), the relative position of impacting and sensing points over the delamination that have great effects on the flexural and impact-echo(thickness) modes were investigated and examined by the parametric finite element analysis. As a result, the flexural modes dominate in the case of a/h > 2 and the thickness mode was more evident when a/h < 2. With regard to the relative position of impact source and sensing point to the defect, the flexural modes dominate even when either the loading or sensing point was over the delamination defect. However, the thickness mode prevails when both the impacting and sensing points are over the solid region beyond the delamination area.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.4
• /
• pp.257-270
• /
• 2002

The Impact-Echo(IE) method has been used to evaluate the integrity of concrete structures. In this method, the P-wave velocity of concrete is a crucial parameter in determining the thickness of concrete lining, the location of cracks or other defects. In many field applications of the IE method, the P-wave velocity is obtained by testing the core or the portion of a structure where the exact thickness is known. Occasionally, however, the core can not be obtained in specific structures and the P-wave velocity determined from core testing may not be a representative value of the structure. This study introduces an IE-SASW method that may determine the P-wave velocity on a surface of each testing area using the Spectral Analysis of Surface Wave (SASW) method. Results obtained from numerical studies are presented in this paper (Part I), and results obtained from experimental studies are presented in the companion paper (Part II). In this paper, numerical analyses using ABAQUS were carried out to investigate the effectiveness and the limitations of the IE-SASW method.

• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.1785-1786
• /
• 2006

본 논문에서 개발한 시스템은 원자력 발전소의 금속파편감시계통(Loose parts monitoring system, LPMS)에서 충격신호의 탐지를 위해 사용되는 하드웨어와 관련이 있는 트리거 판단을 위한 보드이다. LPMS는 원자로 내부에서 발생하는 금속 파편이나 이물질의 존재 여부와 위치를 정확히 찾아내 원자력 발전소의 불필요한 가동중단이나 예기치 않은 안전 사고를 예방 할 수 있는 시스템이다. 본 논문에서 개발한 DAM(Data acquisition module)보드는 LPMS의 하드웨어 중에서 입력된 신호를 디지털로 변환하여 충격신호의 트리거 여부를 판단하는 기능을 한다. DAM은 디지털 필터와 트리거 판단을 위한 알고리즘이 DSP에서 실시간으로 처리되어 DMS의 기능을 업그레이드 하였다. 개발된 시스템은 기존 외국 장비에 비하여 하드웨어 성능이 대폭 향상되었으며 하드웨어의 완전 국산화 개발이라는 특징이 있다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2012.10a
• /
• pp.715-722
• /
• 2012

A structural health monitoring (SHM) technique for locating impact position in a composite plate is presented in this paper. The technique employs a single sensor and spatial focusing properties of time reversal (TR) and inverse filtering (IF). We first examine the focusing effect of back-propagated signal at the impact position and its surroundings through simulation. Impact experiments are then carried out and the localization images are found using the TR and IF signal processing, respectively. Both techniques provide accurate impact location results. Compared to existing techniques for locating impact or acoustic emission source, the proposed methods have the benefits of using a single sensor and not requiring knowledge of material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in the SHM of plate-like structures.

• Information and Communications Magazine
• /
• v.21 no.9
• /
• pp.38-47
• /
• 2004

최근의 인터넷침해사고는 개별시스템에 대한 침입이나 바이러스 등에 의한 파일의 변조 등 개별적인 시스템에 대한 공격보다는 인터넷 기반 등에 대한 직·간접적인 공격으로 진화하였다. 이와 같은 공격의 변화에 따라 인터넷 기반에 공격의 의한 피해가 발생할 경우 막대한 경제적 피해는 물론이고 사회적인 충격 또한 클 것으로 예측된다. 인터넷침해사고대응지원센터는 이와 같은 인터넷 침해사고를 신속히 탐지하고 대응하기 위한 능동적인 정보수집 및 대응체계를 구축하였다. 인터넷침해사고대응체계는 침해사고관련정보 수집, 인터넷의 상황 분석, 상황 전파 및 대응, 복구의 4단계로 구성된다. 이러한 대응체계 구축을 통해 이전에 확인할 수 없었던 인터넷 상황에 대한 정확한 측정 데이터를 확보하고 신속한 침해사고탐지 및 효과적인 대응이 가능하게 되었다.