• The Journal of the Acoustical Society of Korea
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• v.27 no.1
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• pp.47-56
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• 2008

In the detection of an underwater target, there exists an optimal search depth for the sonar systems, at which the Probability of Detection is maximized. The optimal search depth is dependent on the depths of the target and sonar, the sound speed profile, and the bathymetry. In this paper, we address this question in range-dependent environments, particularly for the bathymetry with slope and with warm eddy. For range-dependent bathymetry, the typical sound profile in the East Sea of Korea was used. The detection range was greater when the sonar was located in deep water than in shallow water. As for the case of eddy, mesoscale warm eddy was used, and the detection range was greater when looking out of the warm eddy than when looking into the eddy.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.126-135
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• 2011

In this study, the algorithm for priority area of forest fire surveillance was developed to enhance the effectiveness of fire detection. The high priority surveillance area for forest fire detection was defined as the area with not only low value of viewshed analysis of the lookouts and detection cameras but also high fire occurrence probability. To build the priority map, fuzzy function and map algebra were used. The analysis results of Bonghwa-gun, Gyeongbuk Province, showed that the surveillance priority of central and southern area is higher than north area. This algorithm could be used in the allocation of fire prevention resources and selection of suitable point for new fire detection system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.3
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• pp.37-46
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• 2012

In RADAR and SONAR detection systems, noise environment can be classified into homogeneous and heterogeneous environment. Especially heterogeneous environments are modelled as target masking and clutter edge. Since the variability-index (VI) CFAR, a composed CFAR algorithm, dynamically selects one of the mean-level algorithms based on the VI and the MR (mean ratio) test, it is robust to various environments. However, the VI CFAR still suffers from lowered detection probabilities in heterogeneous environments. To overcome these problems, we propose an improved VI CFAR processor where TM (trimmed mean) CFAR and a sub-windowing technique are introduced to minimize the degradation of the detection probabilities appeared in heterogeneous environments. Computer simulation results show that the proposed method has the better performance in terms of detection probability and false alarm probability compared to the VI CFAR and single CFAR algorithms.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.4
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• pp.35-41
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• 2008

When memory devices are exposed to a space environment. they suffer various effects such as SEU(Single Event Upset). For these reasons, memory systems for space applications are generally equipped with error detection and correction(EDAC) logics against SEUs. In this paper, the error detection and correction strategy in the Mass Memory Unit(MMU) of the STSAT-3 is discussed. The probability equation of un-recoverable SEUs in the mass memory system is derived when the whole memory is encoded and decoded by the RS(10,8) Reed-Solomon code. Also the probability value is analyzed for various occurrence rates of SEUs which the STSAT-3 possibly suffers. The analyzed results can be used to determine the period of scrubbing the whole memory, which is one of the important parameters in the design of the MMU.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.2
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• pp.100-105
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• 2014

This paper comparatively analyze to integration case to have a influence detection range estimation about radar cross section in radar system. This paper estimate detection range used to probability of detection in radar equation that used to swerling case 1 in case of radar cross section is small and used to swerling case 3 in case of radar cross section is large. Through simulation, coherent integration and non-coherent integration about swerling case difference were comparatively analyzed. Through simulation, non-coherent integration case is outstanding detection range and we known that coherent integration don't suitable for detection range estimation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1330-1334
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• 2012

The submarines reach their weakest point when they sail on the surface to operate snorkel and periscope. At this period, however, there lies a high possibility that the submarines are detected by non-acoustic sensors such as radars, IR signatures, and human observations. In this paper, the non-acoustic stealth was adopted on the mast and periscope of submarines so as to overcome their vulnerability of being easily detected in this given situation. First of all, the non-acoustic detection sensors were investigated and the stealth methods were analyzed. And multi-layered structures consisting of RAM layer, IR layer, and Camouflage layer were proposed on the surface of the submarine. As a results, multi-layered structure was suggested with 3~5 mm of a magnetic material such as ferrite for RAM layer, 1~2 mm of ceramic or nickel for IR layer, and sea-blue paint for Camouflage layer.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.113-117
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• 2014

This paper comparatively analyze to integration case to have a influence detection range estimation about radar cross section in radar system. This paper estimate detection range used to probability of detection in radar equation that used to swerling case 1 in case of radar cross section is small and used to swerling case 3 in case of radar cross section is large. Through simulation, coherent integration and non-coherent integration about swerling case difference were comparatively analyzed. In the result of comparative analysis, non-coherent integration case is outstanding detection range and we known that coherent integration don't suitable for detection range estimation.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.3
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• pp.328-336
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• 2017

The goal of this study is simulation of optimal search pattern of ships based on performance surface which are reflected underwater environmental. The process is as follows. First, temporal and spatial environmental database are extracted in complex environment and input hull mounted SONAR system parameters. The environmental database and SONAR system parameters are substituted to SONAR equations, and calculate signal excess, detection probability, detection range. And then, the performance surface, which can be used to provide operational insight of SONAR detection performance, are pictorialized. Finally, optimal search pattern of ships are simulated using genetic algorithm based on performance surface. And then, we certify optimal search pattern in various ways.

• Korean Journal of Remote Sensing
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• v.33 no.5_1
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• pp.547-557
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• 2017

In this paper, a new spectral unmixing based target detection algorithm is proposed which adopted Iterative Error Analysis as a tool for extraction of background endmembers by using the target spectrum to be detected as initial endmember. In the presented method, the number of background endmembers is automatically decided during the IEA by stopping the iteration when the maximum change in abundance of the target is less than a given threshold value. The proposed algorithm does not have the dependence on the selection of image endmembers in the model-based approaches such as Orthogonal Subspace Projection and the target influence on the background statistics in the stochastic approaches such as Matched Filter. The experimental result with hyperspectral image data where various real and simulated targets are implanted shows that the proposed method is very effective for the detection of both rare and non-rare targets. It is expected that the proposed method can be effectively used for mineral detection and mapping as well as target object detection.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.783-790
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• 2018

The frequency-hopping technique is one of the spread-spectrum techniques. Frequency hopping is a communication system in which the carrier frequency channel is hopped within the wideband. Therefore, a frequency-hopping system has such advantages as antijamming and low probability of intercept. This system is often used in military communications. Because frequency-hopping signal detection is difficult, it is an important research issue. A novel detection technique is proposed that can improve detection probability. When the received signal is transformed to a frequency domain sample by fast Fourier transform, spectral leakage lowers the detection probability. This problem can be solved by using the Hamming window, and the detection probability can be increased. However, in a frequency-hopping environment, the windowing technique lowers the detection probability. The proposed method solves this weakness. The simulation results show that the proposed detection technique improves the detection probability by as much as 13 %.