• ETRI Journal
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• 제36권1호
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• pp.12-21
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• 2014

In this paper, we propose a new digital blind in-phase/quadrature-phase (I/Q) mismatch compensation technique for image rejection in a direct-conversion receiver (DCR). The proposed image-rejection circuit adopts DC offset cancellation and a sign-sign least mean squares (LMS) algorithm with a unique step size adaptation both for a fast and precise I/Q mismatch estimation. In addition, several performance-optimizing design considerations related to accuracy, speed, and hardware simplicity are discussed. The implementation of the proposed circuit in an FPGA results in an image-rejection ratio (IRR) of 65 dB, which is the best performance with modulated signals, along with an adaptation time of 0.9 seconds, which is a tenfold increase in the compensation speed as compared to previously reported circuits. The proposed technique will be a promising solution in the area of image rejection to increase both the speed and accuracy of future DCRs.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.645-648
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• 2003

본 논문에서는 영상처리를 이용하여 온라인으로 교통표지판을 인식하는 비젼 시스템을 제안한다. 제안된 시스템은 넓은 두 개의 카메라, 즉 광각렌즈(wide-angle lends)와 망원렌즈(telephoto lends)를 장착하였고, 이미지처리 보드가 있는 PC로 구성되었다. 이 시스템은 색상, 밝기, 형태 둥과 같은 정보를 이용하여 광각이미지의 교통표지판을 추출한 다음, 보다 큰 이미지에서 정확한 표지판 후보영역을 추출하기 위해 망원렌즈에서 포착된 이미지를 이용하여 처리하였다. 또한 간단한 실행과정으로 빠른 인식률을 얻을 수 있었으며, 도로상에서의 실험으로 시스템의 효용성을 입증하였다.

• 한국건설관리학회논문집
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• 제5권4호
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• pp.139-146
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• 2004

Resent removal work for road signs has been labor intensive and required times since it has been done manually using shaving type equipment. While traditional process is conducting, there are traffic jams caused by the passing control, and happened unexpected accidents to workers working at dangerous road circumstance. Besides, in current shaving method, there are high potentialities on the air pollution as well as the explosive accident occurred by using a propane gas. So, as an alternative, we have studied to develop the automatic erasing equipment made up with a high pressure water-jet system and automatic control system, mobile system; Wate-rjet system consists of an intensifier and nozzles to give a high pressure and spray on the sign, and automatic control system is composed of one axis robot using a hydraulic servo actuator controlled by a lever, And as a mobile system, a truck plays an important role for the transport of equipment and the forward movement in a removal process. In this paper, we have analyzed the characteristics of road signs and have investigated current erasing methods in the field. And we have organized and designed automatic erasing equipment, and we have made a basic experiment to find out the optimal spray condition as like the spray distance, spray angle and injection pressure.

• 한국정보통신학회논문지
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• 제8권2호
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• pp.471-476
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• 2004

본 논문에서는 영상처리를 이용하여 온라인으로 교통표지판을 인식하는 비젼 시스템을 제안한다. 제안된 시스템은 넓은 두 개의 카메라, 즉 광각렌즈(wide-angle lends)와 망원렌즈(telephoto lends)를 장착하였고, 이미지처리 보드가 있는 PC로 구성되었다. 이 시스템은 색상, 자기, 형태 등과 같은 정보를 이용하여 광각이미지의 교통표지판을 추출한 다음, 보다 큰 이미지에서 정확한 표지판 후보영역을 추출하기 위해 망원렌즈에서 포착된 이미지를 이용하여 처리하였다. 실험결과로써 수동으로 촬영한 비디오 연속장면에서 포착한 영상을 시용하여 실험한 결과 속도표지판은 추출율 96.5%, 인식률 34.4% 그리고 안내표지판은 추출율 100%, 인식률 40%의 결과를 나타내었다. 또한 간단한 실행과정으로 빠른 인식률을 얻을 수 있었으며, 도로상에서의 실험으로 시스템의 효용성을 입증하였다.

• 한국통신학회논문지
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• 제32권9C호
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• pp.801-809
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• 2007

LDPC 부호는 4G 이동통신 시스템에 적합한 오류 정정 부호이다. 그러나 알고리듬의 특성상 좋은 BER 성능을 위해서는 반복 복호에 의한 많은 연산량이 요구된다. 본 논문에서는 복호지연과 전력 소모에 대한 복호기의 성능을 증가시키기 위하여 반복 복호 횟수를 줄이는 알고리듬에 대하여 제안한다. 제안된 알고리듬은 현재 LLR 복호값과 이전 LLR 복호값 사이의 변화를 측정하고 변화 방향을 예측하며, 패리티 검사식을 만족시켜 수렴속도를 높이도록 LLR 값의 sign 비트를 반전시킨다. 실험결과, 제안한 방법은 BER 성능의 감소 없이 반복 복호 횟수를 약 33% 정도 줄이는 것이 가능하며 감소된 반복 복호 횟수에 비례하여 소모 전력도 감소시킬 수 있다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권1호
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• pp.20-32
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• 2018

Purpose: The purpose of this study is to set up an anomaly detection criteria for sensor data coming from a motorcycle. Methods: Five sensor values for accelerator pedal, engine rpm, transmission rpm, gear and speed are obtained every 0.02 second from a motorcycle. Exploratory data analysis is used to find any pattern in the data. Traditional process control methods such as X control chart and time series models are fitted to find any anomaly behavior in the data. Finally unsupervised learning algorithm such as k-means clustering is used to find any anomaly spot in the sensor data. Results: According to exploratory data analysis, the distribution of accelerator pedal sensor values is very much skewed to the left. The motorcycle seemed to have been driven in a city at speed less than 45 kilometers per hour. Traditional process control charts such as X control chart fail due to severe autocorrelation in each sensor data. However, ARIMA model found three abnormal points where they are beyond 2 sigma limits in the control chart. We applied a copula based Markov chain to perform statistical process control for correlated observations. Copula based Markov model found anomaly behavior in the similar places as ARIMA model. In an unsupervised learning algorithm, large sensor values get subdivided into two, three, and four disjoint regions. So extreme sensor values are the ones that need to be tracked down for any sign of anomaly behavior in the sensor values. Conclusion: Exploratory data analysis is useful to find any pattern in the sensor data. Process control chart using ARIMA and Joe's copula based Markov model also give warnings near similar places in the data. Unsupervised learning algorithm shows us that the extreme sensor values are the ones that need to be tracked down for any sign of anomaly behavior.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.170-171
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• 2015

Resource procurement and material handling are considered as a significant part of construction project especially in large or tall building construction site. There are multiple variables that must be considered in a construction site during finishing work such as movement of materials, equipments, and workers. Therefore, it is difficult for construction workers to find the material handling path solely by intuition. The aim of this study is to propose a real-time path finding model suitable for complicated logistics flow in the field. The model explores the optimal transport path of finishing material with its basis on optimization algorithm, and it determines the direction of the Smart Sign. The proposed model is expected to be utilized for planning of efficient finishing material handling.

• 한국멀티미디어학회논문지
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• 제16권6호
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• pp.735-745
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• 2013

The emergence of Web 2.0 technologies, such as blogs and wiki, enable even naive users to easily create and share content on the Web using freely available content sharing tools. Wide availability of almost free data and promiscuous sharing of content through social networking platforms created a content borrowing phenomenon, where the same content appears (in many cases in the form of extensive quotations) in different outlets. An immediate side effect of this phenomenon is that identifying which content is re-used by whom is becoming a critical tool in social network analysis, including expert identification and analysis of information flow. Internet-scale reuse detection, however, poses extremely challenging scalability issues: considering the large size of user created data on the web, it is essential that the techniques developed for content-reuse detection should be fast and scalable. Thus, in this paper, we propose a $qSign_{lsh}$ algorithm, a mechanism for identifying multi-sentence content reuse among documents by efficiently combining sentence-level evidences. The experiment results show that $qSign_{lsh}$ significantly improves the reuse detection speed and provides high recall.

• 한국정보통신학회논문지
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• 제5권3호
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• pp.543-551
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• 2001

본 논문은 주차판 시스템의 토크 최적화에 대하여 다루었다. 주차판 시스템은 독립된 전원 을 가지고 있어야 하므로 주차판 시스템을 움직이는 데 소요되는 모터 구동력을 최소화하는 것이 문제이다. 따라서 이 문제를 해결하기 위해서는 주차판 시스템의 동적인 방정식을 유도하여야 하며, 비선형 미분방정식을 풀어야 하는 어려움이 있다. 본 논문에서는 동적인 방정식을 유도하였으며, 유전 알고리즘을 이용하여 방정식을 풀었으며, 컴퓨터 모의실험을 통하여 결과의 유용성을 보였다.

• 한국정밀공학회지
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• 제23권9호
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• pp.84-91
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• 2006

The synthesis of optimal controllers for multivariable systems usually requires an accurate linear model of the plant dynamics. Real systems, however, contain nonlinearities and high-order dynamics that may be difficult to model using conventional techniques. This paper presents a novel loaming method for the synthesis of LQR controllers that doesn't require explicit modeling of the plant dynamics. This method utilizes the sign of Jacobian and gradient descent techniques to iteratively reduce the LQR objective function. It becomes easier and more convenient because it is relatively very easy to get the sign of Jacobian instead of its Jacobian. Simulations involving an overhead crane and a hydrofoil catamaran show that the proposed LQR-LC algorithm improves controller performance, even when the Jacobian information is estimated from input-output data.