• 대한임베디드공학회논문지
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• 제15권5호
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• pp.243-249
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• 2020

Event detection in wireless sensor networks is a key requirement in many applications. Acoustic sensors are one of the most frequently used sensors for event detection in sensor networks, but they are sensitive and difficult to handle because they vary greatly depending on the environment and target characteristics of the sensor field. In this paper, we propose a learning-based improvement of CFAR algorithm for increasing node-level event detection performance in acoustic sensor networks, and verify the effectiveness of the designed algorithm by comparing and evaluating the event detection performance with other algorithms. Our experimental results demonstrate the superiority of the proposed algorithm by increasing the detection accuracy by more than 45.16% by significantly reducing false positives by 7.97 times while slightly increasing the false negative compared to the existing algorithm.

• Journal of Communications and Networks
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• 제14권5호
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• pp.518-523
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• 2012

This paper presents new coherent and non-coherent detection methods for the IEEE 802.15.4a low-rate ultra-wideband physical layer with forward error correction (FEC) coding techniques. The coherent detection method involving channel estimation is based on the correlation characteristics of the preamble signal. A coherent receiver uses novel iterated selective-rake (IT-SRAKE) to detect 2-bit data in a non-line-of-sight channel. The non-coherent detection method that does not involve channel estimation employs a 2-bit data detection scheme using modified transmitted reference pulse cluster (M-TRPC) methods. To compare the two schemes, we have designed an IT-SRAKE receiver and a MTRPC receiver using an IEEE 802.15.4a physical layer. Simulation results show the performance of IT-SRAKE is better than that of the M-TRPC by 3-9 dB.

• 센서학회지
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• 제28권1호
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• pp.7-12
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• 2019

Significant progress has been made recently in detection of highly sensitive volatile organic compounds (VOCs) using chemical sensors. Combined with the progress in design of micro sensors array and electronic nose systems, these advances enable new applications for detection of extremely low concentrations of breath-related VOCs. State of the art detection technology in turn enables commercial sensor systems for health care applications, with high detection sensitivity and small size, weight and power consumption characteristics. We have been developing an intelligent electronic nose system for detection of VOCs for healthcare breath analysis applications. This paper reviews our contribution to monitoring of respiratory diseases and to diabetic monitoring using an intelligent electronic nose system for detection of low concentration VOCs using breath analysis techniques.

• 산업융합연구
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• 제21권9호
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• pp.41-48
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• 2023

최근 들어 개인, 기업, 국가 등 사회 전반에 랜섬웨어에 의한 피해가 급증하고 있으며 그 규모도 점차 커지고 있다. 랜섬웨어는 사용자 컴퓨터 시스템에 침입하여 사용자의 중요 파일들을 암호화하여 사용자가 해당 파일들을 사용하지 못하게 하고 그 댓가로 금품을 요구하는 악의적인 소프트웨어이다. 랜섬웨어는 기타 다른 악의적인 코드들에 비해 공격기법이 다양하고 정교하여 탐지가 어렵고 피해 규모가 크기 때문에 정확한 탐지와 해결 방법이 필요하다. 정확한 랜섬웨어를 탐지하기 위해서는 랜섬웨어의 특성들로 학습한 탐지 시스템의 추론엔진이 요구된다. 따라서 본 논문에서는 랜섬웨어의 정확한 탐지를 위해 랜섬웨어가 가지는 특성을 추출하여 분류하는 모델을 제안하고 추출된 특성들의 유사성을 계산하여 특성의 차원을 축소한 다음 축소된 특성들을 그룹화하여 랜섬웨어의 특성으로 공격 도구, 유입경로, 설치파일, command and control, 실행파일, 획득권한, 우회기법, 수집정보, 유출기법, 목표 시스템의 상태 변경으로 분류하였다. 분류된 특성을 기존 랜섬웨어에 적용하여 분류의 타당성을 증명하였고, 차후에 이 분류기법을 이용해 학습한 추론엔진을 탐지시스템에 장착하면 새롭게 등장하는 신종과 변종 랜섬웨어도 대부분 탐지할 수 있다.

• 대한기계학회논문집A
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• 제26권5호
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• pp.864-871
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• 2002

Acoustic emission(AE) technique has been applied to not only mechanical property testing but also on-line monitoring of the entire structure or a limit zone only. Although several AE devices have already been developed for on-line monitoring, the price of these systems is very high and it is difficult for the field to apply yet. In this study, we developed a specially designed PC-based leak detection system using A/D board. In this paper, AE technique has been applied to detect leak for heat exchanger by analyzing the characteristics of signal obtained from leak. It was confirmed that the characteristics of the signal generated by the turbulence of gas in the heat exchanger is narrow band signal having between 130-250kHz. Generally, the amplitude of leak signal is increased as the leak size increasing, but showed no significant change at frequency characteristic. Leak source location can be found by determining for the paint of highest signal amplitude by comparing with several fixed sensors. In this paper, AE results are compared with the PC-based leak detection system using A/D board.

• 한국지구과학회지
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• 제36권5호
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• pp.437-446
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• 2015

Many edge detection methods, based on horizontal and vertical derivatives, have been introduced to provide us with intuitive information about the horizontal distribution of a subsurface anomalous body. Understanding the characteristics of each edge detection method is important for selecting an optimized method. In order to compare the characteristics of the individual methods, this study applied each method to synthetic magnetic data created using homogeneous prisms with different sizes, the numbers of bodies, and spacings between them. Seven edge detection methods were comprehensively and quantitatively analyzed: the total horizontal derivative (HD), the vertical derivative (VD), the 3D analytic signal (AS), the title derivative (TD), the theta map (TM), the horizontal derivative of tilt angle (HTD), and the normalized total horizontal derivative (NHD). HD and VD showed average good performance for a single-body model, but failed to detect multiple bodies. AS traced the edge for a single-body model comparatively well, but it was unable to detect an angulated corner and multiple bodies at the same time. TD and TM performed well in delineating the edges of shallower and larger bodies, but they showed relatively poor performance for deeper and smaller bodies. In contrast, they had a significant advantage in detecting the edges of multiple bodies. HTD showed poor performance in tracing close bodies since it was sensitive to an interference effect. NHD showed great performance under an appropriate window.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.456-460
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• 2020

In this research, a radiation detection backpack to be used discreetly or by a wide range of users was developed using array silicon-photomultiplier (SiPM) and CsI (Tl), and its characteristics were evaluated. The R-squared value, which indicates the responsiveness of a detector based on the signal intensity, was determined to be 0.981, indicating a good linear responsivity. The energy resolutions for gamma radiation energies of Co-57 (122 keV), Ba-133 (356 keV), Cs-137 (662 keV), and Co-60 (1332 keV) were found to be 13.40, 10.50, 6.77, and 3.16%, respectively. These results confirm good energy resolution characteristics. Furthermore, in the case of mixed sources, the gamma radiation peaks were readily distinguishable, and the R-squared value for energy linearity was calculated to be 0.999, demonstrating an exceptional energy linearity. Further research based on the results of this study would enable the commercialization of lightweight SiPM-based wireless radiation detection backpacks that can be used for longer durations by replacing the photomultiplier tube, which is mainly used as the optical sensor in existing radiation detection backpacks.

• 전기전자학회논문지
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• 제18권4호
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• pp.456-462
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• 2014

본 연구는 방사선 검출용 플라스틱 섬광체 검출기의 검출효율을 높이기 위한 섬광체 연마에 관한 연구이다. 플라스틱 섬광체를 이용한 검출기를 제작하여 4단계의 연마 과정으로 섬광체 절단면에서 광손실을 감소시켰다. 이때 연마단계와 검출 효율에 대한 상관관계를 구하여 검출 특성을 평가하였다. 연마단계에 따른 검출 효율을 측정한 결과 연마하지 않은 섬광체와 비교하여 4단계의 연마 과정을 모두 연마한 섬광체를 이용한 검출기의 검출 효율이 최대 7.57배 증가하는 것을 확인하였고 각 단계 별로 연마한 섬광체를 이용하여 제작한 검출기에서도 방사선의 세기, 거리, 위치에 대한 검출 특성에서도 연마하지 않은 섬광체에 비하여 좋은 검출 특성을 보였다.

• 센서학회지
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• 제13권3호
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• pp.188-194
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• 2004

With a remarkable advance in CMOS (complimentary metal-oxide-semiconductor) process technology, a variety of vision sensors with signal processing circuits for complicated functions are actively being developed. Especially, as the principles of signal processing in human retina have been revealed, a series of vision chips imitating human retina have been reported. Human retina is able to detect the edge and motion of an object effectively. The edge detection among the several functions of the retina is accomplished by the cells called photoreceptor, horizontal cell and bipolar cell. We designed a CMOS vision chip by modeling cells of the retina as hardwares involved in edge and motion detection. The designed vision chip was fabricated using $0.6{\mu}m$ CMOS process and the characteristics were measured. Having reliable output characteristics, this chip can be used at the input stage for many applications, like targe tracking system, fingerprint recognition system, human-friendly robot system and etc.

• 한국항해학회지
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• 제22권4호
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• pp.59-67
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• 1998

A quick and automatic detection with no harm to the goods is very important task for improving quality control, process control and labour reduction. In real fields of industry, defect detection is mostly accomplished by skillful workers. A narrow band eliminating spatial filter having characteristics of removing the specified spatial frequency is developed by the author, and it is proved that the filter has an excellent ability for on-line and real time detection of surface defect. By the way,. this spatial filter shows a ripple phenominum in filtering characteristics. So, it is necessary to remove the ripple component for the improvement of filter gain, moreover efficiency of defect detection. The spatial filtering method has a remarkable feature which means that it is able to set up weighting function for its own sake, and which can to obtain the best signal relating to the purpose of the measurement. Hence, having an eye on such feature, theoretical analysis is carried out at first for optimal design of narrow band eliminating spatial filter, and secondly, on the basis of above results spatial filter is manufactured, and finally advanced effectiveness of spatial filter is evaluated experimentally.