• The Journal of the Acoustical Society of Korea
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• v.28 no.8
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• pp.761-767
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• 2009

The detection of target echoes in a sonar image is usually difficult since reverberation is originated by the returns reflected around the boundary and volumes. Under the scenario of the target presence around the reverberation, the detection performance of existing algorithms is degraded. Since they have a similar statistical features. But proposed detector gives improvement existing algorithms Under this scenario. In this paper, 4 segmentation contrast box algorithm using maximum contrast value is proposed based on statistical segmentation, which gives better detection performance in the sense of reducing false alarms. The simulations validate the effectiveness of the proposed algorithm.

• Journal of Communications and Networks
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• v.11 no.2
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• pp.115-121
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• 2009

In cognitive radio (CR) systems, cognitive users can use the frequency bands when the primary users are not present. Hence, reliable detection of available spectrum is foundation of cognitive radio technology. To ensure unimpaired operation of primary users, cooperative spectrum sensing is needed. To reduce the network overhead of cooperative spectrum sensing, a novel cooperative spectrum sensing algorithm based on credibility is proposed. In particular, the close-form expressions for probability of detection and false-alarm are derived for the novel algorithm, and expression for the average overhead used for cooperation is given. The thresholds design method for the algorithm is also discussed. The conclusion is proved by computer simulations.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.73-76
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• 2000

We investigate the stepwise parallel processing of the serial search which can success the co]1 search at low Ec/Io. The single path Rayleigh fading channel which is worst-case channel model is considered. The typical 3-step cell search is used. The probabilities of detection, miss and false alarm for each step are used in closed forms based on the statistics of CDMA noncoherent demodulator output. The optimal power allocation to each channel and The optimal number of post-detection integrations for each step is obtained. Also, the cumulative probability distribution of the average eel] search time for serial search methods are compared.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.119-122
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• 2010

Cognitive Radioo(CR)기술은 주파수 자원을 효율적으로 이용하기 위해 Joseph Mitora가 개념을 적립한 것으로 유비쿼터스 시대의 부족한 주파수 자원을 극복 할 수 있는 기술로 각광받고 있다. 이와 같은 무선인지 기술(CR)을 도입하기 위한 핵심적인 요소는 부사용자(Secondary User)가 주사용자(Primary User)의 통신을 방해하지 않도록 주파수 점유 여부를 정확하게 판단하는 Spectrum Sensing기술이다. 이 스펙트럼 센싱 기술에 두 가지 종류의 에러가 발생하는데 하나는 미검출 오류(miss error)이고 또 하나는 오경보 오류(false alarm error)이다. 따라서 본 논문은 이 두 가지를 합친 검출 오류(detection error)를 최소화 하기위해 협력 스펙트럼 센싱(Cooperative spectrum sensing)에서 몇 명 이상의 부사용자가 주사용자가 사용중이라 검출하였을 때 최종 결정이 주사용자가 사용한다고 결론 짓는 것이 최적인지를 수학적으로 분석하고 그 최적의 K값을 사용하여 전체 시스템의 성능을 향상 시키는 방법을 제시 한다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.1
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• pp.92-99
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• 1996

2단계 접속 논리(two-stage cascaded logic)는 관측 지역 내에 새로이 출현한 표적에 대한 트랙을 만드는 대표적인 방법중의 하나이다. 2단계 접속 논리의 트랙 생성 (track formation)에 관한 성능 평가 방법 및 결과는 Bar-Schalom에 의해 발표된 바가 있으나, 그 연구 결과는 트랙 생성 성능을 도출할 때 클러터로 인한 오경보율(false alarm probability)을 무시한다는 가정에 기초한 것이기 때문에, 오경보율이 높은 경우에는 적용 할 수 없다는 단점을 지닌다. 이에 본 논문에서는 오경보율을 고려하여 2단계 접속 논리의 트랙 생성 성능을 평가 할 수 있는 개선된 방법을 제시하고자 한다. 그리고 2단계 접속 논리에서 사용하는 데이터 연관(data association)기법으로 트랙 분리(track splitting)기법과 최 근접 데이터 선택 기법(nearest neighbor rule)을 사용하는 경우에 대하여 각각의 성능 평가 결과를 몇 가지 예시하고자 한다.

• Journal of Korea Multimedia Society
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• v.22 no.11
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• pp.1300-1312
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• 2019

BSTRACT In this paper, PM10 forecast model using DNN(Deep Neural Network) is developed for Seoul region. The previous Julian forecast model has been developed using weather and air quality data of Seoul region only. This model gives excellent results for accuracy and false alarm rates, but poor result for POD(Probability of Detection). To solve this problem, an WA(Wide Area) forecasting model that uses Chinese data is developed. The data is highly correlated with the emergence of high concentrations of PM10 in Korea. As a result, the WA model shows better accuracy, and POD improving of 3%(D+0), 21%(D+1), and 36%(D+2) for each forecast period compared with the Julian model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.1998-2016
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• 2012

Reliable spectrum sensing algorithm is a fundamental component in cognitive radio. In this paper, a non-cooperative spectrum sensing algorithm which needs only one cognitive radio node named CORDIC (Coordinate Rotation Digital Computer) Jacobi based method is proposed. The algorithm computes the eigenvalues of the sampled covariance of received signal mainly by shift and additional operations, which is suitable for hardware implementation. Based the latest random matrix theory (RMT) about the distribution of the limiting maximum and minimum eigenvalue ratio, the relationship between the probability of false alarm and the decision threshold is derived. Simulations and discussions show the method is effective. Real captured digital television (DTV) signals and Universal Software Radio Peripheral (USRP) are also employed to evaluate the performance of the algorithm, which prove the proposed algorithm can be applied in practical spectrum sensing applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.2
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• pp.383-393
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• 1996

This paper considers the evaluation of the ecquistion performance for an accesschannel preamble based on a random access procedure of direct sequence code division multiple access(DS/CDMA) reverse link. The parallel acquistion technique that employs the single-well detection scheme and the multiple-dwell(double-dwell) detection scheme is mentioned. The acquisition performance for two detection schemes is compared in therms of the acquisition probability and the acquisition time. The parallel acquisition is done by a bank of N parallel I/Q noncoherent correlators. Expressions on the detection, false alarm, and miss probabilities of the single-dwell and multiple-dwell(double-well) detection schemes are derived for multiple H$_{1}$ cells and multipath Rayleight fading channel. comparing the single-dwell detection scheme with the multiple-dwell(double-dwell) detection scheme in the case of employing the parallel acquisition technique in the reverse link,the numerical results show that the single-dwell detection scheme deomonstrates a better performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10A
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• pp.949-955
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• 2008

In this paper, we propose the improved energy detector using adaptive thresholds in cognitive radio system, in order to compensate the weak points of the existing energy detector in the distorted communication environment. In addition, by investigating the several parameters we analyze its performance. The numerical results show the proposed method may get the performance gain, when the mobile speed is slow (3 km/h) as well as the false alarm probability is low ($P_f=10^{-1}$).

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.43.1-43.1
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• 2019

We perform the Lomb-Scargle Periodogram analysis to protostars identified by the JCMT Transient Survey, which monitors 8 nearby star forming regions. The observations have been done monthly for over 3 years using SCUBA-2 (the Submillimetre Common User Bolometer Array 2) in two wavelengths, 450 and $850{\mu}m$. Under the threshold of 1% False Alarm Probability, we found 16 variable sources including EC53, which is the first variable protostar detected by the JCMT Transient Survey. Most of the variable sources are cataloged as protostars (classified via the Spitzer data, Megeath et al. 2012; Dunham et al. 2015), but SerpS-MM19, which has a clear 1-year period, is a candidate of a first hydrostatic core (Maury et al. 2011; Young et al. 2018).