• Interaction and multiscale mechanics
• /
• 제3권4호
• /
• pp.321-331
• /
• 2010

A new technique is proposed for bridge structural damage detection based on spatial wavelet analysis of the time history obtained from vehicle body moving over the bridge, which is different from traditional detection techniques based on the bridge response. A simply-supported Bernoulli-Euler beam subjected to a moving spring-mass unit is established, with the crack in the beam simulated by modeling the cracked section as a rotational spring connecting two undamaged beam segments, and the equations of motion for the system is derived. By using the transfer matrix method, the natural frequencies and mode shapes of the cracked beam are determined. The responses of the beam and the moving spring-mass unit are obtained by modal decomposition theory. The continuous wavelet transform is calculated on the displacement time histories of the sprung-mass. The case study result shows that the damage location can be accurately determined and the method is effective.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
• /
• 제4권1호
• /
• pp.31-37
• /
• 2001

In this paper, an integrated damage identification system (IDIS) is proposed to locate and size damage in real structures. The application of the IDIS to real structures includes the measurement of modal responses, the construction of damage-detection models, and the implementation of measurements and models into the damage-detection process. Firstly, the theory of the damage identification method is outlined. Secondly, the schematic and each component of the IDIS are described. Finally, the practicality of the IDIS is verified from experiments on two different bridge-models, a model plate-grider and a model truss.

• 전산구조공학
• /
• 제7권3호
• /
• pp.153-166
• /
• 1994

구조물의 손상예측정확도를 모델불확실성의 함수로 산정하는 방법론이 제시되었다. 먼저, 구조물의 손상발생위치과 크기를 결정할 수 있는 알고리즘의 요약되고 모델불확실성과 손상발견정확도를 측정하는 방법들이 제시되었다. 다음으로, 실존구조물의 손상발견정확도에 미치는 모델불확실성의 영향을 산정하는 방법론이 제시되었다. 마지막으로, 한개의 진동모드가 측정된 Plate-Girder교량을 사용하여 이같은 산정방법론의 적합성이 예증되었다.

• 전기학회논문지
• /
• 제62권1호
• /
• pp.120-126
• /
• 2013

This paper proposes a novel scheme of fault detection and self-recovery for space-borne dual ring counters subject to transient faults. The considered ring counter is equipped with hardware redundancy, but it has a limited output domain where direct access to the current state is unavailable. We employ the theory of corrective control to detect any transient fault occurring to the counter bits and to realize immediate self-recovery of the ring counter back to the normal state. The structure of the fault-tolerant controller is designed to be minimal regardless of the counter size. To validate the applicability, we implement the proposed system on a commercial FGPA board.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 G
• /
• pp.3221-3223
• /
• 1999

OAEs are low-level sounds produced by cochlea as part of the normal hearing process. OAEs can be measured with a microphone placed in the outer ear-cannel. We can diagnose cochlea's condition by using OAEs. To diagonose it's condition, however, is difficult by reason of OAEs' tiny. Thus, It need to a method using latency which essential diagnosing a time-element of OAEs. This study proposes a latency detection algorithm using 7-QMF for more effective detection of latency, 7-QMF designed by wavelet theory can process signal without a losses of information. The latency-detector based on 7-QMF is superior to former method.

• 한국정보처리학회논문지
• /
• 제6권2호
• /
• pp.522-533
• /
• 1999

본 논문에서는 피지 파라미터와 퍼지 추론을 포함한 화자 인식 알고리즘을 제안한다. 시간영역에서 검출 알고리즘의 장점인 잡음에 강인함을 가진 PVPF 법을 제안하여 피치를 검출한다. 또한 화자 인식에서 특징량들의 애매성을 표현하고 인식하는 방법으로 퍼지 이론을 도입하였다. PVPF는 음의 시간적인 특징을 이용하여 국부적으로 봉우리와 골을 이룬다는 것을 이용한 계산량이 적고 잡음에 강인한 피치 검출법이다.

• Nuclear Engineering and Technology
• /
• 제53권10호
• /
• pp.3256-3263
• /
• 2021

The main steam line break accident is an essential initiating event of the pressurized water reactor. In present work, the fuzzy set theory and the signal-based fault detection method has been used to detect the occurrence and diagnosis of the location and break area for the small scale MSLB. The models are validated by the AP1000 accident simulator based on MAAP5. From the test results it can be seen that the proposed approach has a rapid and proper response on accident detection and location diagnosis. The method proposed to evaluate the break area shows good performances for small scale MSLB with the relative deviation within ±3%.

• International Journal of Computer Science & Network Security
• /
• 제23권6호
• /
• pp.147-154
• /
• 2023

Network intrusion refers to any unauthorized penetration or activity on a computer network. This upsets the confidentiality, integrity, and availability of the network system. One of the major threats to any system's availability is a Denial-of-Service (DoS) attack, which is intended to deny a legitimate user access to resources. Therefore, due to the complexity of DoS attacks, it is increasingly important to abstract and describe these attacks in a way that will be effectively detected. The automaton theory is used in this paper to implement a SYN Flood detection system based on Time-Dependent Finite Automata (TDFA).

• 반도체디스플레이기술학회지
• /
• 제22권2호
• /
• pp.81-86
• /
• 2023

Recently, there has been an increased demand for light-emitting diode (LED) due to the growing emphasis on environmental protection. However, the use of GaN-based sapphire in LED manufacturing leads to the generation of defects, such as dislocations caused by lattice mismatch, which ultimately reduces the luminous efficiency of LEDs. Moreover, most inspections for LED semiconductors focus on evaluating the luminous efficiency after packaging. To address these challenges, this paper aims to detect defects at the wafer stage, which could potentially improve the manufacturing process and reduce costs. To achieve this, image processing and deep learning-based defect detection techniques for Sapphire Epi-Wafer used in Green LED manufacturing were developed and compared. Through performance evaluation of each algorithm, it was found that the deep learning approach outperformed the image processing approach in terms of detection accuracy and efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권10호
• /
• pp.4661-4680
• /
• 2016

Cognitive radio (CR) technology is an effective solution to the spectrum scarcity issue. Collaborative spectrum sensing is known as a promising technique to improve the performance of spectrum sensing in cognitive radio networks (CRNs). However, collaborative spectrum sensing is vulnerable to spectrum data falsification (SSDF) attack, where malicious users (MUs) may send false sensing data to mislead other secondary users (SUs) to make an incorrect decision about primary user (PUs) activity, which is one of the key adversaries to the performance of CRNs. In this paper, we propose a coalition based malicious users detection (CMD) algorithm to detect the malicious user in CRNs. The proposed CMD algorithm can efficiently detect MUs base on the Geary'C theory and be modeled as a coalition formation game. Specifically, SSDF attack is one of the key issues to affect the resource allocation process. Focusing on the security issues, in this paper, we analyze the power allocation problem with MUs, and propose MUs detection based power allocation (MPA) algorithm. The MPA algorithm is divided into two steps: the MUs detection step and the optimal power allocation step. Firstly, in the MUs detection step, by the CMD algorithm we can obtain the MUs detection probability and the energy consumption of MUs detection. Secondly, in the optimal power allocation step, we use the Lagrange dual decomposition method to obtain the optimal transmission power of each SU and achieve the maximum utility of the whole CRN. Numerical simulation results show that the proposed CMD and MPA scheme can achieve a considerable performance improvement in MUs detection and power allocation.