• 대한치과의사협회지
• /
• 제49권8호
• /
• pp.461-471
• /
• 2011

The detection of carious lesions is a key point to apply appropriate preventive measures or operative treatment of dental caries. A laser fluorescence device DIAGNOdent$^{(R)}$ (KaVo, Biberach, Germany) has also been shown to be of additional clinical value in the detection of initial caries. This report focus on the DIAGNOdent$^{(R)}$ for caries detection. DIAGNOdent$^{(R)}$ irradiate visible red light at a wavelength of 655 nm to elicit near-infrared fluorescence from caries lesion. This device is known as a reproducible method for caries detection, with good sensitivity and specificity especially for caries detection on occlusal and accessible smooth surfaces. DIAGNOdent$^{(R)}$ tended to be more sensitive method of detecting occlusal dentinal caries, however, showed more false-positive diagnoses than the visual inspection. So Clinician should not use the device as a clinician's primary diagnostic method and it is recommended that the device should be used in the decision-making process in relation to the diagnosis of caries as a second opinion in cases of doubt after visual inspection. The trend of modern dentistry would be a preventive approach rather than invasive treatment of the disease. This is possible only with early detection and respective preventive measures, DIAGNOdent$^{(R)}$ can help the changes.

• Journal of Power Electronics
• /
• 제17권5호
• /
• pp.1327-1337
• /
• 2017

Photovoltaic (PV) systems are influenced by disproportionate impacts on energy production caused by frequent mismatch cases. The occurrence of multiple maximum power points (MPPs) adds complexity to the tracking process in various PV systems. However, current maximum-power point tracking (MPPT) techniques exhibit limited performance. This paper introduces an enhanced simulated annealing (ESA)-based GMPPT technique against multiple MPP issues in P-V curve with different PV system structures. The proposed technique not only distinguishes global and local MPPs but also performs rapid convergence speed and high tracking accuracy of irradiance changing and restart capability detection. Moreover, the proposed global maximum power tracking algorithm can be applied in the central converter of DMPPT and hybrid PV system to meet various application scenarios. Its effectiveness is verified by simulation and test results.

• Smart Structures and Systems
• /
• 제4권6호
• /
• pp.779-794
• /
• 2008

Observer-based fault detection and isolation (FDI) filter design method is a model-based method. By carefully choosing the observer gain, the residual outputs can be projected onto different independent subspaces. Each subspace corresponds to the monitored structural element so that the projected residual will be nonzero when the associated structural element is damaged and zero when there is no damage. The key point of detection filter design is how to find an appropriate observer gain. This problem can be interpreted in a geometric framework and is found to be equivalent to the problem of finding a decentralized static output feedback gain. But, it is still a challenging task to find the decentralized controller by either analytical or numerical methods because its solution set is, generally, non-convex. In this paper, the concept of detection filter and iterative LMI technique for decentralized controller design are combined to develop an algorithm to compute the observer gain. It can be used to monitor structural element state: healthy or damaged. The simulation results show that the developed method can successfully identify structural damages.

• 한국컴퓨터정보학회논문지
• /
• 제24권1호
• /
• pp.73-83
• /
• 2019

In this paper, we propose the augmented reality(AR) based driving navigation based on robust lane detection method to dynamic environment changes. The proposed technique uses the detected lane position as a marker which is a key element for enhancing driving information. We propose Symmetrical Local Threshold(SLT) algorithm which is able to robustly detect lane to dynamic illumination environment change such as shadows. In addition, by using Morphology operation and Connected Component Analysis(CCA) algorithm, it is possible to minimize noises in the image, and Region Of Interest(ROI) is defined through region division using a straight line passing through several vanishing points We also propose the augmented reality aided visualization method for Interchange(IC) and driving navigation using reference point detection based on the detected lane coordinates inside and outside the ROI. Validation experiments were carried out to assess the accuracy and robustness of the proposed system in vairous environment changes. The average accuracy of the proposed system in daytime, nighttime, rainy day, and cloudy day is 79.3% on 4600 images. The results of the proposed system for AR based IC and driving navigation were also presented. We are hopeful that the proposed research will open a new discussion on AR based driving navigation platforms, and thus, that such efforts will enrich the autonomous vehicle services in the near future.

• Smart Structures and Systems
• /
• 제16권1호
• /
• pp.67-79
• /
• 2015

Acoustic emission analysis is an effective technique for monitoring the evolution of damage in a structure. An experimental analysis on a set of reinforced concrete beams under flexural loading was carried out. A mixed AE analysis method which used both parameter-based and signal-based techniques was presented to characterize and identify different failure mechanisms of damage, where the signal-based analysis was performed by using the Hilbert-Huang transform. The maximum instantaneous energy of typical damage events and the corresponding frequency characteristics were established, which provided a quantitative assessment of reinforced concrete beam using AE technique. In the bending tests, a "pitch-catch" system was mounted on a steel bar to assess bonding state of the steel bar in concrete. To better understand the AE behavior of bond-slip damage between steel bar and concrete, a special bond-slip test called pullout test was also performed. The results provided the basis of quantitative AE to identify both failure mechanisms and level of damages of civil engineering structures.

• 대한교통학회지
• /
• 제34권3호
• /
• pp.278-290
• /
• 2016

연속교통류 운영 및 설계에서는 최대통과교통류율에 따른 교통류 상태변화 분석이 중요하다. 최대통과교통류율은 연속교통류 운영상태를 평가함에 있어 기준이 되고 있으며, 병목현상과 같은 지 정체 발생시 최대통과교통류율이 급격히 감소하게 된다. 현재까지 이러한 연속교통류 운영과 관련된 다양한 연구들이 수행되었지만, 변화되는 교통량을 명확하게 식별하지 못하고 있다. 이에 본 연구에서는 교통운영 및 설계 등의 다양한 연구를 수행하는 데 있어 가장 중요한 실시간 교통량 변화 검지 방법론에 대한 연구를 실시한다. 이를 위하여 도시고속도로 자유로 구간의 24시간 레이더검지기의 시계열 자료를 이용하며, 교통류 상태 구분에는 통계적 기법의 일환인 터닝포인트 분석(Tunring Point Analysis, 이하 TPA)를 적용한다. TPA는 베이지안 접근법(bayesian approach)을 이용하며, 차량도착은 포아송 분포로 가정한다. 분석대상 구간에 대한 터닝포인트(Turning Point, 이하 TP)를 도출하였으며, 교통량이 변화되는 시점을 확인할 수 있었다. 또한 실시간 교통상태변화 검지를 위한 방법으로 TP지속시간을 설정하여 분석을 실시하였으며, 실시간으로 교통량의 변화를 검지하였다. 이는 기존의 직관적이고 경험적인 접근법의 한계를 극복할 수 있는 장점을 가지며, 실시간으로 교통량 변화를 식별할 수 있어 램프미터링(ramp-metering), 가변차로 등의 교통운영관리에 적용이 가능하다.

• ETRI Journal
• /
• 제43권4호
• /
• pp.603-616
• /
• 2021

Over the last few years, autonomous vehicles have progressed very rapidly. The odometry technique that estimates displacement from consecutive sensor inputs is an essential technique for autonomous driving. In this article, we propose a fast, robust, and accurate odometry technique. The proposed technique is light detection and ranging (LiDAR)-based direct odometry, which uses a spherical range image (SRI) that projects a three-dimensional point cloud onto a two-dimensional spherical image plane. Direct odometry is developed in a vision-based method, and a fast execution speed can be expected. However, applying LiDAR data is difficult because of the sparsity. To solve this problem, we propose an SRI generation method and mathematical analysis, two key point sampling methods using SRI to increase precision and robustness, and a fast optimization method. The proposed technique was tested with the KITTI dataset and real environments. Evaluation results yielded a translation error of 0.69%, a rotation error of 0.0031°/m in the KITTI training dataset, and an execution time of 17 ms. The results demonstrated high precision comparable with state-of-the-art and remarkably higher speed than conventional techniques.

• 융합정보논문지
• /
• 제10권6호
• /
• pp.19-27
• /
• 2020

본 연구에서는 나날이 발전하는 카메라의 해상도 기술과 SNS의 이미지 공유를 통해서 고해상도로 찍은 이미지를 손쉽게 구할 수 있고, 이미지를 통해서 사람의 손가락 지문을 손쉽게 채취하여 이를 악용할 수 있다는 가능성을 고려해 이를 방지하는 기술을 제시한다. 이 기술을 개발하기 위해서는 Python 언어를 이용한 Opencv와 opencv안의 Blur 처리를 해주는 라이브러리 등을 사용한다. 우선 이미지에서 손을 찾아주기 위해서 딥러닝 기반의 학습된 Hand Key point Detection 알고리즘을 사용한다. 이 알고리즘을 이용해 손가락 마디를 찾아 이 마디의 좌표를 이용해 이미지에서의 손가락 지문 부위만을 따로 blur 처리를 해줌으로써 원본 이미지에서의 손상을 최소화하면서 손가락 지문을 보호할 수 있다. 향후 정확한 손가락 추적 알고리즘의 개발로 스마트폰 카메라 app의 내부 옵션으로 사용하여 고해상도의 이미지에서의 지문을 보호할 수 있을 것이다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
• /
• pp.125-125
• /
• 2000

An Empirical approach to determine a road-surface condition is presented The road-surface condition thus provided includes the detection of not only friction coefficient, but also abrupt surface-profile changes such as pitfalls and bumpers The former plays a key role in establishing the appropriate control strategy, while the latter allows to minimize unnecessary brake intervention induced by the aforementioned jut. In this paper, we use an empirically chosen variable, namely. the time-rate of change of vehicle speed estimated from the point where ABS engaged to the point where measurement taken Experimental results shoe that the proposed method is effective to infer various control variables critical for the control of ABS.

• 정보처리학회논문지:소프트웨어 및 데이터공학
• /
• 제4권5호
• /
• pp.225-230
• /
• 2015

본 논문에서는 키 프레임 영상과 SURF 특징점 기반의 시각 단어들을 이용한 효과적인 실시간 시각 루프 결합 탐지기 VILODE를 제안한다. 시각 루프 결합 탐지기는 과거에 지나온 위치들 중 하나를 다시 재방문하였는지를 판단하기 위해, 새로운 입력 영상을 이미 지나온 위치들에서 수집한 과거 영상들과 모두 비교해보아야 한다. 따라서 새로운 위치나 장소를 방문할수록 비교 대상 영상들이 계속해서 증가하기 때문에, 일반적으로 루프 결합 탐지기는 실시간 제약과 높은 탐지 정확도를 동시에 만족하기 어렵다. 이러한 문제점을 극복하기 위해, 본 시스템에서는 입력 영상들 중에서 의미 있는 것들만을 선택해 이들만을 비교하는 효과적인 키 프레임 선택 방법을 채택하였다. 따라서 루프 탐지에 필요한 영상 비교를 대폭 줄일 수 있다. 또한 본 시스템에서는 루프 결합 탐지의 정확도와 효율성을 높이기 위해, 키 프레임 영상들을 시각 단어들로 표현하고, DBoW 데이터베이스 시스템을 이용해 키 프레임 영상들에 대한 색인을 구성하였다. TUM 대학의 벤치마크 데이터들을 이용한 실험을 통해, 본 논문에서 제안한 시각 루프 결합 탐지기의 높은 성능을 확인할 수 있었다.