• 정보처리학회논문지B
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• 제15B권6호
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• pp.501-506
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• 2008

기존 스네이크 알고리즘은 에너지 함수의 정의에 의해 복잡한 객체의 윤곽을 추출하는데 어려움이 있고, GVF 방법은 에너지 맵 계산 시간이 많이 소요되는 문제점이 있다. 본 논문에서는 빠르고, 복잡한 객체의 윤곽을 잘 추출하는 방법을 제안한다. 객체 윤곽의 복잡도는 곡률로 정의하여 곡률 값이 임계치 이상이면 스네이크 포인트를 추가하여 객체의 윤곽을 추출하였다. 다수의 복잡한 영상에 실험을 통해 계산속도 및 윤곽 추출 성능을 개선하는 결과를 보여준다.

• 제어로봇시스템학회논문지
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• 제6권1호
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• pp.57-65
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• 2000

In this paper, a model reference adaptive control for the atomic force microscope (AFM) of tapping mode is investigated. The dynamics between the AFM system and al sample is mathematically modeled as a second order spring-mass-damper system with oscillatory inputs. The attractive and repulsive forces between the tip of the AFM system and the sample are derived using the Lennard-Jones potential energy. By non-dimensionalizing the displacement of the tip and the input frequency, the chaotic behavior near a resonance frequency is better depicted through the non-dimensionalized equations. Four nonlinear analysis techniques, a phase portrait, sensitive dependence on initial conditions, a power spectral density function, and a Pomcare map are investigated. Because the equations of motion derived in this paper involve unknown parameter values such as the damping effect of the air and the interaction constants between materials, the standard model reference adaptive control is adopted. Two control objectives, the prevention of chaos and the tracking of reference signal, are pursued. Simulation results are included.

• 대한임베디드공학회논문지
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• 제10권5호
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• pp.281-296
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• 2015

This paper describes a novel disaster evacuation system using embedded systems such as smart devices for crisis and emergency management. In indoor environments deployed with the Bluetooth Low Energy(BLE) beacons, smart devices detect their indoor positions from beacon messages and interact with Map Server(MS) and Route Server(RS) in the Internet over the LTE and/or Wi-Fi functions. The MS and RS generate an optimal path to the nearest emergency exit based on a novel graph generation method for less route computation, called the Disaster Evacuation Graph(DEG), for each smart device. The DEG also enables efficient processing of some constraints in the computation of route, such as load balancing in situation of different capacities of paths or exits. All data interfaces among three system components, the MS, RS, smart devices, have been defined for modular implementation of our disaster evacuation system. Our experimental system has been deployed and tested in our building thoroughly and gives a good evidence that the modular design of the system and a novel approach to compute emergency route based on the DEG is competitive and viable.

• 한국재료학회지
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• 제12권1호
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• pp.44-47
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• 2002

DV(Discrete Variation)-X${\alpha}$ cluster calculation was employed to calculate the electronic states of ${\gamma}'- Fe_4N$ which was one of iron nitride phases synthesized from plasma ion nitriding to improve surface hardness and wear resistance. The result of calculated electron density of states for Fe was similar to the result of band calculation. The cluster used for calculation of electronic states of ${\gamma}'-Fe_4N$ was based on $Fe_{14}N$ cluster which comprises 15 atoms. Finally the electronic states of ${\gamma}'- Fe_4N$ such as net-charge, band order, energy level, electron wave-function, and contour map for electron density were derived by the calculation.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.38-50
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• 2018

Spatio-temporal load forecasting (STLF) is a foundation for building the prediction-based power map, which could be a useful tool for the visualization and tendency assessment of urban energy application. Constructing one point-forecasting model for each electricity cell in the geographic space is possible; however, it is unadvisable and insufficient, considering the aggregation features of electricity cells and uncertainties in input variables. This paper presents a new STLF method, with a data-driven framework consisting of 3 subroutines: multi-level clustering of cells considering their aggregation features, load regression for each category of cells based on SLS-SVRNs (sparse least squares support vector regression networks), and interval forecasting of spatio-temporal load with sampled blind number. Take some area in Pudong, Shanghai as the region of study. Results of multi-level clustering show that electricity cells in the same category are clustered in geographic space to some extent, which reveals the spatial aggregation feature of cells. For cellular load regression, a comparison has been made with 3 other forecasting methods, indicating the higher accuracy of the proposed method in point-forecasting of spatio-temporal load. Furthermore, results of interval load forecasting demonstrate that the proposed prediction-interval construction method can effectively convey the uncertainties in input variables.

• 한국통신학회논문지
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• 제27권8A호
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• pp.796-804
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• 2002

본 논문에서는 방향성필터뱅크(Directional Filter Bank; DFB)에 기반하여 지문영상을 해석하여 처리하는 새로운 방법을 제안한다. 지문에서 융선의 방향성는 방향성지도를 구성하고, 이로부터 방향성 필터링을 통한 영상 향상을 행하는 등 지문 영상을 해석하는 전처리과정에서 매우 중요한 요소이다. DFB는 입력영상을 방향성대역영상으로 분해한 다음 이로부터 원영상을 완전하게 복원하는 필터이다. 본 논문에서는 DFB를 이용하여 지문영상을 여러 개의 방향성대역영상으로 분해하고, 이로부터 국부 방향성 에너지를 정의한 다음, 이를 기반으로 방향성지도의 제작, 영상분할, 특이점추출 및 영상개선의 처리과정들을 일관되게 수행하는 알고리듬을 제안한다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.475-477
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• 2010

IEEE 802.11에 정의된 전력 절약 메카니즘에서 모든 노드들은 동일한 ATIM(Ad hoc Traffic Indication Map) 윈도우 크기와 동일한 비이콘(beacon) 간격을 사용한다. ATIM 윈도우 크기는 처리율과 에너지 소모에 크게 영행을 미치기 때문에 고정된 ATIM 윈도우 크기는 좋은 성능을 나타내지 못한다. 본 논문에서는 네트워크 상태에 따라 ATIM 윈도우 크기를 조절하는 기법을 제시한다. 제시된 기법은 네트워크 특성을 반영하기 위해 (m,k)-firm 스트림 기법을 적용하였다. 제시된 기법의 성능을 평가하기 위해 ns-2 시뮬레이터를 이용한 성능 평가를 수행했다. 수행된 결과를 보면 제시된 프로토콜은 기존의 프로토콜 보다 많은 양의 에너지 절약을 하고 있음을 볼 수 있다.

• 한국기계가공학회지
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• 제20권1호
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• pp.16-24
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• 2021

A laser-engineered net shaping (LENS) process is a representative directed energy deposition process. Deposition characteristics of the LENS process are greatly dependent on the process parameters. The present paper preliminarily investigates deposition characteristics of Inconel 718 superalloy on S45C structural steel using a LENS process. The influence of process parameters, including the laser power and powder feed rate, on the characteristics of the bead formation and the dilution in the vicinity of the deposited region is examined through repeated experiments. A processing map and feasible deposition conditions are estimated from viewpoints of the aspect ratio, defect formation, and the dilution rate of the deposited bead. Finally, an appropriate deposition condition considering side angle, deposition ratio, and buy-to-fly (BTF) is predicted.

• 대한임베디드공학회논문지
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• 제17권6호
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• pp.309-317
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• 2022

In this paper, we propose a machine learning-based copy-move forgery detection network with dual branches. Because the rotation or scaling operation is frequently involved in copy-move forger, the conventional convolutional neural network is not effectively applied in detecting copy-move tampering. Therefore, we divide the input into rotation-invariant and scaling-invariant features based on the wavelet coefficients. Each of the features is input to different branches having the same structure, and is fused in the combination module. Each branch comprises feature extraction, correlation, and mask decoder modules. In the proposed network, VGG16 is used for the feature extraction module. To check similarity of features generated by the feature extraction module, the conventional correlation module used. Finally, the mask decoder model is applied to develop a pixel-level localization map. We perform experiments on test dataset and compare the proposed method with state-of-the-art tampering localization methods. The results demonstrate that the proposed scheme outperforms the existing approaches.

• 한국지반환경공학회 논문집
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• 제24권3호
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• pp.15-21
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• 2023

국내에는 낙석시설 관련 기준이 마련되어 있지만, 낙석방지망 흡수에너지의 경우 실물 시험을 통해 낙석의 통과여부 및 낙석방지망 파괴 여부로부터 흡수에너지를 평가하게 되어있다. 기존의 PVC 코팅망이 낙석 하중을 충분히 억제하지 못하고 찢어지는 현상이 빈번하게 발생하는데, 이를 방지하기 위해서 고강도 선제 포획망을 개발하였다. 본 연구에서는 기존의 PVC 코팅망과 개발된 고강도 선제 포획망(1,000MPa, 2,000MPa)의 현장 테스트를 통해 성능을 분석하였다.