• 한국강구조학회 논문집
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• 제11권1호통권38호
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• pp.1-11
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• 1999

본 논문에서는 강구조물의 제작 및 시공에서 용접이음부의 고품질을 확보하기 위하여 강구조물 용접이음부 외부결함의 자동검출에 관한 화상처리 알고리즘을 개발한다. 개발 알고리즘은 광학계의 적절한 배치에 의해 얻어지는 4매의 입력화상을 이용하여 기존의 기법에서 검출할 수 없었던 용접이음부 외부결함을 검출할 수 있음을 보인다. 용접 외부결함이 존재하는 시험편을 제작하고 실험을 통하여 개발 알고리즘의 유용성을 확인하였다. 또한 검출된 용접외부결함의 분류 결과를 육안검사 결과와 비교하였다.

• 제어로봇시스템학회논문지
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• 제9권10호
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• pp.755-767
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• 2003

This paper proposes a robust fault-tolerant control framework for robot manipulators to maintain the required performance and achieve task completion in the presence of both partial joint failures and complete joint failures and uncertainties. In the case of a complete joint failure or free-swinging joint failure causing the complete loss of torque on a joint, a fully-actuated robot manipulator can be viewed as an underactuated robot manipulator. To detect and identify a complete actuator failure, an on-line fault detection operation is also presented. The proposed fault-tolerant control system contains a robust adaptive controller overcoming partial joint failures based on robust adaptive control methodology, an on-line fault detector detecting and identifying complete joint failures, and a robust adaptive controller overcoming partial and complete joint failures, and so eventually it can face and overcome joint failures and uncertainties. Numerical simulations are conducted to validate the proposed robust fault-tolerant control scheme.

• 한국항행학회논문지
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• 제15권3호
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• pp.392-404
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• 2011

본 논문에서는 최근 4세대 이동통신에서 논의 되고 있는 기술인 셀 간 협력 통신이 가능한 다중 셀 환경에서 상향링크에서의 다중 사용자 신호 검출기술에 대해서 다루었다. 먼저 기존 검출 기술로 ML, ZF, MMSE 그리고 SIC 등을 다루었고, 보통 ML은 최적의 성능을 보이지만, 복잡도가 지수적으로 증가하며, ZF나 MMSE는 간단하지만 성능이 떨어지며, SIC는 복잡하고 오류전파 현상이 발행 할 수 있는 문제점을 가지고 있다. 이에 기존의 ZF/MMSE 에 비해서는 성능 개선이 이루어지면서, 복잡도를 유지 또는 감소시킬 수 있는 구조 제안을 위해서 ZF/MMSE 방식과 ML 의 적용구조를 단순화 시킨 부분 ML 복호 방식을 결합한 검출 방식을 제안하였다. 모의실험 결과, 제안방식은 ZF/MMSE 기반의 SIC 방식에 비해 BER 성능이 개선 또는 유지 되었으며, 복잡도 측면에서 감소하는 효과를 보였으며, 또한 복잡도 감소는 협력 기지국 및 안테나 수가 증가할수록 더 감소 효과가 커질 수 있음을 알 수 있었다.

• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.124-128
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• 2014

We derive joint probability density functions (JPDFs) for two adjacent data from direct-detection optical receivers in dense wavelength-division multiplexing systems. We show that the decision using two data per bit can increase the receiver sensitivity compared with the conventional decision. Our JPDFs can be used for software-defined optical receivers enhancing the receiver sensitivities for intensity-modulated channels.

• 한국통신학회논문지
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• 제12권5호
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• pp.428-438
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• 1987

本 論文은 大氣 空間에서 信號場과 雜音場을 處理하기 위하여 point-detector array檢波 시스템을 構成한 것이다. 또 variance 및 covariance Circuit도 구성했다. 이것들을 이용하여 測定한 直接檢波 最大出力은 理論値와 잘 一致함을 確認하였고 또한 實驗値는 joint-Gaussian理論曲線과 一致하였다.

• 한국멀티미디어학회논문지
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• 제21권3호
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• pp.333-341
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• 2018

In this paper, we propose an algorithm to automatically detect gait's joints. The proposed method classifies gait's types into front gait and flank gait so as to automatically detect gait's joints. And then according to classified types, the proposed applies joint extracting algorithm to input images. Firstly, we split input images into foreground image using difference images of Hue and gray-scale image of input and background one and extract gait's object. The proposed method classifies gaits into front gait and flank gait using ratio of Face's width to torso's width. Then classified gait's type, joints are detected 10 at front gait and detected 7~8 at flank gait. The proposed method is applied to the camera's input and the result shows that the proposed method automatically extracts joints.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권11호
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• pp.5527-5545
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• 2019

Through-wall ultra-wide band (UWB) radar has been considered as one of the preferred and non-contact technologies for the targets detection owing to the better time resolution and stronger penetration. The high time resolution is a result of a larger of bandwidth of the employed UWB pulses from the radar system, which is a useful tool to separate multiple targets in complex environment. The article emphasised on human subject localization and detection. Human subject usually can be detected via extracting the weak respiratory signals of human subjects remotely. Meanwhile, the range between the detection object and radar is also acquired from the 2D range-frequency matrix. However, it is a challenging task to extract human respiratory signals owing to the low signal to clutter ratio. To improve the feasibility of human respiratory signals detection, a new method is developed via analysing the standard deviation based kurtosis of the collected pulses, which are modulated by human respiratory movements in slow time. The range between radar and the detection target is estimated using joint time-frequency analysis (JTFA) of the analysed characteristics, which provides a novel preliminary signature for life detection. The breathing rates are obtained using the proposed accumulation method in time and frequency domain, respectively. The proposed method is validated and proved numerically and experimentally.

• 터널과지하공간
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• 제19권1호
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• pp.52-63
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• 2009

대규모 암반 절리면의 거칠기를 구하는 여러 가지 방법이 있으나, 길이 10 cm의 절리를 Barton 등이 제안한 표준절리면곡선과 비교하여 절리면 거칠기계수 JRC (joint roughness coefficient)를 결정하고 대규모 절리의 길이에 따라 보정하는 것이 가장 일반적인데, 적합한 표준 절리면곡선을 선택할 때 측정자에 따라 달라자는 경우가 많다. 따라서 대규모 암반 절리면의 거칠기 JRC는 길이에 따른 보정 없이 직접 측정하는 것이 정확할 것이나 측정방법에 한계가 있다. 본 연구에서는 대규모 암반절리를 LIDAR (light detection and ranging)로 스캔하고 절리의 길이 L과 절리면 상의 돌출부(asperity) 높이의 진폭 a를 이용하여 대규모 암반 절리의 거칠기계수 JRC를 구하였다. 그 결과 대규모의 암반 절리면에서도 절리의 길이 증가에 따라 거칠기 계수 JRC가 감소하는 비 정상상태(non-stationary)의 치수효과와 거칠기 측정방향에 따라 절리면 거칠기계수 JRC가 다른 것을 확인하였다.

• 국제강구조저널
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• 제18권4호
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• pp.1200-1209
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• 2018

In this study, a probabilistic framework of the damage assessment of pipelines subjected to extreme hazard scenario was developed to mitigate the risk and enhance design reliability. Nonlinear 3D finite element models of T-joint systems were developed based on experimental tests with respect to leakage detection of black iron piping systems, and a damage assessment analysis of the vulnerability of their components according to nominal pipe size, coupling type, and wall thickness under seismic wave propagations was performed. The analysis results showed the 2-inch schedule 40 threaded T-joint system to be more fragile than the others with respect to the nominal pipe sizes. As for the coupling types, the data indicated that the probability of failure of the threaded T-joint coupling was significantly higher than that of the grooved type. Finally, the seismic capacity of the schedule 40 wall thickness was weaker than that of schedule 10 in the 4-inch grooved coupling, due to the difference in the prohibition of energy dissipation. Therefore, this assessment can contribute to the damage detection and financial losses due to failure of the joint piping system in a liquid pipeline, prior to the decision-making.

• ETRI Journal
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• 제34권6호
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• pp.892-899
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• 2012

We analyze a wideband spectrum in a cognitive radio (CR) network by employing the optimal adaptive multiband sensing-time joint detection framework. This framework detects a wideband M-ary quadrature amplitude modulation (M-QAM) primary signal over multiple nonoverlapping narrowband Gaussian channels, using the energy detection technique so as to maximize the throughput in CR networks while limiting interference with the primary network. The signal detection problem is formulated as an optimization problem to maximize the aggregate achievable secondary throughput capacity by jointly optimizing the sensing duration and individual detection thresholds under the overall interference imposed on the primary network. It is shown that the detection problems can be solved as convex optimization problems if certain practical constraints are applied. Simulation results show that the framework under consideration achieves much better performance for M-QAM than for binary phase-shift keying or any real modulation scheme.