• Smart Structures and Systems
• /
• 제16권4호
• /
• pp.607-621
• /
• 2015

Wireless sensor technology has been opened up numerous opportunities to advanced health and maintenance monitoring of civil infrastructure. Compare to the traditional tactics, it offers a better way of providing relevant information regarding the condition of building structure health at a lower price. Numerous domestic buildings, especially longer-span buildings have a low frequency response and challenging to measure using deployed numbers of sensors. The way the sensor nodes are connected plays an important role in providing the signals with required strengths. Out of many topologies, the dense and sparse topologies wireless sensor network were extensively used in sensor network applications for collecting health information. However, it is still unclear which topology is better for obtaining health information in terms of greatest components, node's size and degree. Theoretical and computational issues arising in the selection of the optimum topology sensor network for estimating coverage area with sensor placement in building structural monitoring are addressed. This work is an attempt to fill this gap in high-rise building structural health monitoring application. The result shows that, the sparse topology sensor network provides better performance compared with the dense topology network and would be a good choice for monitoring high-rise building structural health damage.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.1378-1379
• /
• 2008

In this study, we developed intelligent spacer built in the internal type UHF PD sensors. 3-Dimensional electro-magnetic simulations were performed to analyze electric-field distribution of the single-phase GIS and three-phase GIS. After considering the spacer's specification, Sensor structures were designed and analyzed using the 3-D EM Simulator. As a result of the simulation the internal type UHF PD sensors were built in. Performance of the sensor built into real scale GIS spacer was measured in terms of return loss and detected Max voltage. And we identified a character of the intelligent spacer by using 5pC partial discharge cell.

• 한국정밀공학회지
• /
• 제14권7호
• /
• pp.67-72
• /
• 1997

Recently, in order to achieve high flexibility of manufacture, monitoring and control strategies of a new type have been developed. Since the generation of built-up edge on the cutting tool damages the surface finish of the workpiece, the monitoring system of built-up edge is an important process monitoring. In this study, the analyzing methods of cutting force signal to detect the built-up edge during cutting process are described. The cutting force signals are analyzed using the mean, standard deviation and mean to standard deviation of this cutting signals. We can obtain the guide to detect the built-up edge during turning process.

• 센서학회지
• /
• 제19권4호
• /
• pp.328-335
• /
• 2010

We have designed and fabricated an active pixel sensor(APS) using an optimized n-well/gate-tied p-channel metal oxide semiconductor field effect transistor(PMOSFET)-type photodetector with a built-in transfer gate. This photodetector has a floating gate connected to n-well and a built-in transfer gate. The photodetector has been optimized by changing the length of the transfer gate. The APS has been fabricated using a 0.35 ${\mu}m$ standard complementary metal oxide semiconductor(CMOS) process. It was confirmed that the proposed APS has a wider dynamic range than the APS using the previously proposed photodetector and a higher sensitivity than the conventional APS using a p-n junction photodiode.

• 한국항공우주학회지
• /
• 제36권6호
• /
• pp.550-557
• /
• 2008

영구히 장착된 배열 압전 능동 센서를 사용하여 복합재 보강판의 볼트 구멍에 있는 층간분리 손상을 탐지하였다. 다양한 신호처리 기법을 사용하여 국부적인 수직하중에 의하여 발생한 볼트 구멍 주위의 눈에 보이지 않는 작은 층간분리를 탐지하였다. 배열 압전 센서를 사용하여 진단신호를 생성하였으며, 응답신호를 측정하였다. 응답신호를 신호 처리하여 손상에 민감한 특성들을 추출하였다. 이 특성들을 사용하여 손상 지수를 계산하였고, 손상 지수를 사용하여 손상의 유무와 위치를 추정하였다.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2015년도 춘계학술발표대회
• /
• pp.212-213
• /
• 2015

Data aggregation is a fundamental problem in wireless sensor networks that has attracted great attention in recent years. On constructing a robust algorithm for minimizing data aggregation delay in wireless sensor networks, we consider limited transmission range sensors and approximate the minimum-delay data aggregation tree which can only be built in networks of unlimited transmission range sensors. The paper proposes an adaptive method that can be applied to maintain the network structure in case of a sensor node fails. The data aggregation tree built by the proposed scheme is therefore self-healing and robust. Intensive simulations are carried out and the results show that the scheme could adapt well to network topology changes compared with other approaches.

• 한국멀티미디어학회논문지
• /
• 제12권12호
• /
• pp.1778-1786
• /
• 2009

Many sensor network applications have been developed for smart home, disaster management, and a wide range of other applications. These applications, however, generally assume a fixed base station as well as fixed sensor nodes. Previous research on sensor networks mainly focused on efficient transmission of data from sensors to fixed sink nodes. Recently there has been active research on mobile sink nodes, sink mobility is one of the most comprehensive trends for information gathering in sensor networks, but the research of an environment where both fixed sink nodes and mobile sinks are present at the same time is rather scarce. This paper proposes a scheme for context-aware by ubiquitous devices with the sink functionality added through fixed sinks under a previously-built, cluster-based multi-hop sensor network environment. To this end, clustering of mobile devices were done based on the fixed sinks of a previously-built sensor network, and by using appropriate fixed sinks, context gathering was made possible. By mathematical comparison with TTDD routing protocol, which was proposed for mobile sinks, it was confirmed that performance increases by average 50% in energy with the number of mobile sinks, and with the number of movements by mobile devices.

• 전자공학회논문지C
• /
• 제34C권8호
• /
• pp.49-63
• /
• 1997

This paper presents a current sensor that detects defects in CMOS integrated circuits using the current testing technique. The current sensor is built in a CMOS integrated circuit to test an abnormal current. The proposed circuit has a very small impact on the performance of the circuit under test during the normal mode. In the testing mode, the proposed circuit detects the abnormal current caused by permanent manufacturing defects and determines whether the circuit under test is defect-free or not. The proposed current sensor is simple and requires no external voltage and current sources. Hence, the circuit has less area and performance degradation, and is more efficient than any previous works. The validity and effectiveness are verified through the HSPICE simulation on circuits with defects.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
• /
• pp.39-45
• /
• 2000

This paper describes the fundamental investigations on the in-process monitoring techniques focused on Acoustic Emission(AE) based on analytical method. Experiments were conducted on a CNC lathe using conventional carbide insert tools under various cutting conditions. As the result of this study a suggestion is given about the multi-purpose use of AE-signals detected with a single sensor for the monitoring of tool wear, built-up edge and chatter vibration in turning process.

• 제어로봇시스템학회논문지
• /
• 제18권5호
• /
• pp.445-452
• /
• 2012

With the increasing number of high-rise and large-scale buildings, modern buildings are becoming intelligent, and are incurring high construction costs and requiring careful maintenance. Maintenance works for high-rise buildings significantly depend on human labor, unlike other construction processes that are gradually being automated. The resulting accidents may produce very high social and economic losses. To address this problem, herein, this paper proposes robotic building maintenance system using multi-robot concept, in specific, cleaning a building facade which is directly subjected to minimize human labor; that improves the process efficiency and economic feasibility. The sensor for detecting contamination of building's outer-wall glass is proposed; Kalman filter was used for estimating robots' status with the contamination of the window glass. Task allocation of the sensor based multi-robots for an effective way of task execution is introduced and the feasibility was verified through the simulations.