• 한국신뢰성학회지:신뢰성응용연구
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• 제10권1호
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• pp.11-24
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• 2010

Lighting industry is rapidly being developed as the ubiquitous society based on sensor network emerges. This kind of paradigm shift brings the society convergence of technologies which leads to smart lighting system as well as the integration of interior and sensibility control. However, standards for sensors have not been firmly established, and problems related to quality and malfunction have been brought up, thereby calling for careful approach to the enhancement and assessment of reliability of the item. In this article reliability assessment criteria for sensor module for lighting fixtures is established in terms of performance assessment criterion and reliability assessment criterion.

• 센서학회지
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• 제6권2호
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• pp.131-136
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• 1997

The ISFET(ion sensitive field effect transistor), a semiconductor ion sensor, has many advantages over conventional ion sensors. Various single-sensor type ISFET pH-meters have been developed. However, they could not be applied in fields because their performances are directly affected by the sensor condition. With only one sensor, the system could be easily damaged from environmental factors, and reliability of it is decreased. Therefore, a 4-channel PH-meter system is proposed to improve the reliability of ISFET pH-meter. It has 4 ISFETS as ion sensor, and a software which contains a new calibration and measurement algorithm appropriate to the system. The reliability of the system was proved by measuring hydrogen ion concentration in the pH standard solutions and buffer solutions.

• Journal of Platform Technology
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• 제9권1호
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• pp.32-39
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• 2021

기존 환경측정기기는 전자파 및 친환경 제품 인증, 내구성 시험 위주이며, 센서 신뢰성 검증 및 측정 데이터에 대한 검증은 형식 승인 및 등록, 인수시험, 초기교정, 주기시험 등을 통해 센서 성능평가 위주로 수행된다. 본 플랫폼은 각 타겟 센서별 성능평가 뿐만 아니라 센서의 데이터 신뢰성에 대한 검증체계 지원 ICT 기반 환경 모니터링 센서 신뢰성 검증 체계를 구축하였다. 환경 정보에 대한 센서 데이터를 수집할 센서보드를 제작하였고 센서 및 데이터 신뢰성 평가 및 검증 서비스 체계를 규격화 하였다. 또한, ICT 기반 센서 데이터 신뢰성 평가 및 검증을 위해 LoRa 통신을 이용한 센서 데이터 플랫폼 모니터링 프로토타입을 제작하였고 이를 스마트 시티 등에 실증 테스트하였다. 해당 시스템을 통해 받은 데이터 분석을 위해 머신러닝을 이용하여 최적화 알고리즘 개발하였다. 이를 통해 신뢰성 검증을 위한 센서 빅데이터 분석시스템을 구축하였고 통합 평가 및 검증 시스템의 기반을 마련하였다.

• Journal of information and communication convergence engineering
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• 제16권1호
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• pp.38-42
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• 2018

In this paper, we consider measurement allocation problem in a spatially correlated sensor field. Our goal is to determine the probability of each sensor's being measured based on its contribution to the estimation reliability; it is desirable that a sensor improving the estimation reliability is measured more frequently. We consider a spatial correlation model of a sensor field reflecting transmission power limit, noise in measurement and transmission channel, and channel attenuation. Then the estimation reliability is defined distortion error between event source and its estimation at sink. Motivated by the correlation nature, we model the measurement allocation problem into a cooperative game, and then quantify each sensor's contribution using Shapley value. Against the intractability in the computation of exact Shapley value, we deploy a randomized method that enables to compute the approximate Shapley value within a reasonable time. Besides, we envisage a measurement scheduling achieving the balance between network lifetime and estimation reliability.

• 한국통신학회논문지
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• 제30권9A호
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• pp.850-857
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• 2005

센서 네트워크는 저전력 저가격 소형 근거리 무선통신이 가능한 다기능 노드를 사용하여, 센싱, 데이터 프로세싱, 통신을 할 수 있도록 구성된 네트워크를 말한다. 센서 네트워크의 설계에서는 주로 네트워크 생존시간을 증가시키기 위한 전력 소모를 줄이는 것을 고려하였지만, 실제 응용에서는 최종 사용자에게 노드에서 감지한 정보를 신뢰적으로 전달하는 것이 가장 중요하다. 기존의 다중경로를 이용한 신뢰성있는 전송(Reliable information forwarding using multiple paths in sensor networks: ReInForM)은 에러가 일어나기 쉬운 환경에서 요구 신뢰도에 맞게 데이터를 전송하는 알고리즘이지만, 채널 에러율이 높아지고 소스와 싱크간의 흡 수가 늘어날수록 전송 오버헤드가 급격하게 늘어난다. 본 논문에서는 중간 싱크 노드 및 소스 노드를 이용한 신뢰성 있는 전송 (Reliable transmission using intermediate source nodes in sensor networks :ReTrust)을 제안한다. 성능분석과 시뮬레이션을 통해 ReTrust 알고리즘은 오버헤드는 줄이면서 요구 신뢰도를 만족함을 보인다.

• Physical Therapy Rehabilitation Science
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• 제11권3호
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• pp.311-320
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• 2022

Objective: To investigate the reliability and validity of static balance measurements using an acceleration sensor and a gyroscope sensor in smart phone inertial sensors. Design: Equivalent control group pretest-posttest. Methods: Subjects were forty five healthy adults aged twenty to fifty-years-old who had no disease that could affect the experiment. After pre-test, all participants wore a waist band with smart phone, and conducted six static balance measurements on the force plate twice for 35 seconds each. To investigate the test-retest reliability of both smart phone inertial sensors, we compared the intra-correlation coefficient (ICC 3, 1) between primary and secondary measurements with the calculated root mean scale-total data. To determine the validity of the two sensors, it was measured simultaneously with force plate, and the comparision was done by Pearson's correlation. Results: The test-retest reliability showed excellent correlation for acceleration sensor, and it also showed excellent to good correlation for gyroscope sensor(p<0.05). The concurrent validity of smartphone inertial sensors showed a mostly poor to fair correlation for tandem-stance and one-leg-stance (p<0.05) and unacceptable correlation for the other postures (p>0.05). The gyroscope sensor showed a fair correlation for most of the RMS-Total data, and the other data also showed poor to fair correlation (p<0.05). Conclusions: The result indicates that both acceleration sensor and gyroscope sensor has good reliability, and that compared to force plate, acceleration sensor has unacceptable or poor correlation, and gyroscope sensor has mostly fair correlation.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권4호
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• pp.297-306
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• 2006

In this paper, We presented the algorithm for estimating a reliability between nodes in wireless distributed sensor networks (DSN). To estimate the reliability between nodes, we first modeled DSN as probability graph. Links of the graph are always reliable and the probability of node failure is independent. After all possible simple path which can be established between two nodes are examined, we perform sharp operation to remove repetition event between two nodes. Using probability for each variable of the minimized Boolean equation, we present the reliability formula.

• Smart Structures and Systems
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• 제14권2호
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• pp.145-158
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• 2014

The objective of this study is to improve the survivability and reliability of the FBG sensor network in the structural health monitoring (SHM) system. Therefore, a model reconstruction soft computing recognition algorithm based on support vector regression (SVR) is proposed to achieve the high reliability of the FBG sensor network, and the grid search algorithm is used to optimize the parameters of SVR model. Furthermore, in order to demonstrate the effectiveness of the proposed model reconstruction algorithm, a SHM system based on an eight-point fiber Bragg grating (FBG) sensor network is designed to monitor the foreign-object low velocity impact of a CFRP composite plate. Simultaneously, some sensors data are neglected to simulate different kinds of FBG sensor network failure modes, the predicting results are compared with non-reconstruction for the same failure mode. The comparative results indicate that the performance of the model reconstruction recognition algorithm based on SVR has more excellence than that of non-reconstruction, and the model reconstruction algorithm almost keeps the consistent predicting accuracy when no sensor, one sensor and two sensors are invalid in the FBG sensor network, thus the reliability is improved when there are FBG sensors are invalid in the structural health monitoring system.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권1호
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• pp.37-50
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• 2006

The accelerated life tests of the catalytic gas sensor were performed at three different gas concentration conditions. From the test data, the power-Weibull model was estimated and the acceleration factor between test condition 25%LEL(Lowe Explosive Limit) and use condition 5%LEL was about 3 according to this acceleration model. Using this acceleration factor, life test specification for qualifying that B10 lifetime of the catalytic gas sensor meets the goal lifetime (5 years) was designed.

• 센서학회지
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• 제24권5호
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• pp.326-330
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• 2015

The recent development of Sensor technology has broadened its applications to many fields of industry including railroad. The sensor technology enables the railroad system to monitor and control. This paper suggests the sensor based system design for evaluating and improving the reliability and safety of the ICT system. For this purpose, the reliability and the level of safety integrity of a general gateway have been predicted quantitatively and the supplementary design has been proposed for RAMS improvement. RAMS requirements for each life cycle stipulated in IEC 62278. RAMS activity is capable of producing significant and effective reductions in operation costs and time.