• Journal of Korean Society for Geospatial Information Science
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• v.19 no.3
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• pp.49-56
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• 2011

Because urban areas change rapidly, it is necessary to reflect urban changes in a digital map database in a timely manner. To address these issues, LiDAR data was used to detect changes in urban area buildings. The purpose of this study is to detect object-based building change using LiDAR data and existing digital maps, and classify change types. In the study, we classified change type using overlay and shape comparison with building layer of the digital maps and point-based extracted building outline from the LiDAR data. When applying the overlay method, we were able to increase the accuracy and objectivity of the change detection process throughout an adaptive threshold applied to each object. In the experiments, it was demonstrated that classifying and detecting changes in urban areas using the proposed method can provide superior classification accuracy compared with the existing methodology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1113-1119
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• 2006

For a multi-user OFDM system in mobile channels which requires low-complexity in adaptive resource allocations, resource allocation algorithm using multi-threshold is proposed. The allocation scheme, which is performed by the multi-threshold values in descending order, considers only subcarriers over each threshold level. Moreover, some subcarriers with the lowest channel gain can be· removed in the present threshold level within the constraint of satisfaction of the required data rate, in order to allocate them to the other users when the allocation process of next threshold is executed. As a result, the proposed bandwidth and subcarrier algorithm has better system performances than the conventional allocation schemes in terms of required power and processing time, which is expected as a technique that improves the spectral efficiency of OFDM systems in a mobile environment.

• Journal of Satellite, Information and Communications
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• v.8 no.1
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• pp.61-65
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• 2013

In this paper, we propose system model to solve conventional threshold problem of using fixed false alarm for energy spectrum sensing. Spectrum sensing reliability is ensured when Secondary user have high SNR. Thus, it is not reasonable using fixed optional false alarm without considering CR user's SNR. So, we propose adaptive threshold method. adaptive threshold is decided by controling FA according to CR user's SNR.

• The Journal of the Acoustical Society of Korea
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• v.27 no.7
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• pp.386-393
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• 2008

This paper proposes a new approach for speech enhancement in highly nonstationary noisy environments. The spectral subtraction (SS) is a well known technique for speech enhancement in stationary noisy environments. However, in real world, noise is mostly nonstationary. The proposed method uses an auto control parameter for an adaptive threshold to work well in highly nonstationary noisy environments. Especially, the auto control parameter is affected by a linear function associated with an a posteriori signal to noise ratio (SNR) according to the increase or the decrease of the noise level. The proposed algorithm is combined with spectral subtraction (SS) using a hangover scheme (HO) for speech enhancement. The performances of the proposed method are evaluated ITU-T P.835 signal distortion (SIG) and the segment signal to-noise ratio (SNR) in various and highly nonstationary noisy environments and is superior to that of conventional spectral subtraction (SS) using a hangover (HO) and SS using a minimum statistics (MS) methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.1-8
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• 2016

Recently, buildings tend to be large size, complex shape and functional. As the size of buildings is becoming massive, the need for structural health monitoring(SHM) technique is ever-increasing. Various SHM techniques have been studied for buildings which have different dynamic characteristics and are influenced by various external loads. Generally, the visual inspection and non-destructive test for an accessible point of structures are performed by experts. But nowadays, the system is required which is online measurement and detect risk elements automatically without blind spots on structures. In this study, in order to consider the response of non-linear structures, proposed a signal feature extraction and the adaptive threshold setting algorithm utilized to determine the abnormal behavior by using statistical methods such as control chart, root mean square deviation, generalized extremely distribution. And the performance of that was validated by using the acceleration response of structures during earthquakes measuring system of forced vibration tests and actual operation.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.478-480
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• 2001

본 논문에서는 실제 도로 영상에서 움직이는 물체를 검출하고 판별하기 위한 새로운 방법을 제안한다. 제안된 방법은 연속된 영상의 차영상에 적응적 임계간을 적용하여 움직임이 있는 후보 영역을 검출한다. 검출된 후보영역에 관심의 대상이 되는 물체의 포함 여부를 판별하기 위해 신경망을 사용한다. 신경망의 입력으로 사용되는 특징 벡터들의 차원을 줄이기 위해, 후보 영역의 스케일 공간 웨이블릿 특징 벡터 (scale-space wavelet feature vector)들을 사용한다. 제안된 방법은 비디오 기반의 응용 프로그램에 유용하게 이용될 수 있으며 특히, 시간에 따라 조명이 변하거나 잡음이 포함된 비디오 영상에 대해 좋은 결과를 얻을 수 있다.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.606-611
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• 2007

최근 u-healthcare 서비스 분야에서 단일 시점의 일반화된 치료가 아닌 장시간 개개인의 특성이 반영된 진료와 의료 서비스에 대한 관심이 증가하고 있다. 그러나 기존의 생체 신호 해석은 임상적인 실험을 통해 얻은 표준화된 임계치를 이용해 분석하는 일관된 판단 방법이 주를 이루었다. 본 논문에서는 미래형 홈 환경에서 사용자에 따라 다른 신호 해석을 지원하는 사용자 적응적 생체 신호 해석 방법을 제안한다. 생체 신호 해석은 사용자의 컨텍스트와 환경 컨텍스트를 통합하는 모듈과, 지식표현 기법을 적용한 개인화된 추론 모듈로 구성된다. 제안된 방법은 사용자 정황 정보를 고려하여 사용자 적응적인 생체 신호 해석을 지원하며, 환경 컨텍스트를 고려하여 환경의 변화에 영향을 최소화하는 생체 신호 해석을 지원한다. 또한 사상의학 이론을 생체신호 해석에 동적으로 적용할 수 있는 틀을 제공한다. 이는 추후 미래형 홈 환경에서 다양한 종류의 센서와 함께 개인화된 맞춤형 재택 건강관리 서비스에 활용할 수 있다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.632-639
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• 2012

Ad-hoc networks can be used various environment, which it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio(CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In conventional CR based ad-hoc network, it uses constant threshold value to detect primary user signal, so the results become not reliable. In this paper, to solve this problem, we apply adaptive threshold value to the CR based ad-hoc network, and adaptive threshold is immediately changed by SNR(Signal to Noise Ratio). From the simulation results, we confirmed that proposed algorithm has the greatly better detection probabilities than conventional CR based ad-hoc network.

• Proceedings of the IEEK Conference
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• 2000.06d
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• pp.123-126
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• 2000

In this paper, we propose new watermarking technique using weighting factor decision method in the watermark embedding step and adaptive threshold decision method in the watermark extracting step. In our method, we are determined weighting factor in simple by calculating distance between pixel coefficient and neighborhood pixel coefficients and threshold is adaptively determined by searching the minimized extract error value using histogram of difference value.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.379-381
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• 2001

본 논문은 카메라의 움직임이 있는 영상에서 움직이는 사람의 얼굴을 검출하는 방법을 제안한다. 제안된 방법에서, 얼굴 영역을 찾기 위해 피부 색깔 정보와 움직임 정보를 이용한다. 카메라의 움직임을 어파인 모션 모델(Affine Motion Model)을 이용해 제거한 후, 적응적 임계치(adaptive thresholding)를 통해 얻어진 움직임 영역 내에서만 피부 색깔 모델(skin color model)을 이용해 얼굴 영역을 검출한다. 제안된 방법은 시간에 따라 조명이 변하거나 잡음이 포함된 영상에서도 좋은 결과를 얻을 수 있다.