• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.4
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• pp.365-373
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• 2019

An Image Infra-Red(IIR) seeker is widely used for precision guided munitions to provide intelligent and precise target detection in terms of high kill probability. However, there have been issues in determining the performance versus cost trade-offs due to high cost of seeker comparing to other units of the munitions. In this paper, performance/cost evaluations have been carried out to find the most cost-effective solution for developing the IIR seekers. The relationships between the critical parameters and cost are investigated to determine the optimal point which represents the low cost with high performance. It is expected that the presented approach will be able to be used for guidelines to select the appropriate IIR seeker for the given operating conditions and can be useful to estimate the cost effectiveness of the precision guided munitions at early design stage.

• Journal of the Korea Society for Simulation
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• v.31 no.4
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• pp.11-22
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• 2022

Unlike a short-range, a long-range underwater acoustic communication(UWAC) uses low frequency signal and deep sound channel to minimize propagation loss. In this case, even though communication signals are modulated using a covert transmission technique such as spread spectrum, it is hard to conceal the existence of the signals. The unconcealed communication signal can be utilized as active sonar signal by enemy and presence of underwater vehicles may be exposed to the interceptor. Since it is very important to maintain stealthiness for underwater vehicles, the detection probability of friendly underwater vehicles should be considered when interceptor utilizes our long-range UWAC signal. In this paper, we modeled a long-range UWAC environment for analyzing the detection performance of underwater vehicles and proposed the region of interest(ROI) setup method and the measurement of detection performance. By computer simulations, we yielded parameters, analyzed the detection probability and the detection performance in ROI. The analysis results showed that the proposed detection performance analysis method for underwater vehicles could play an important role in the operation of long-range UWAC equipment.

• The Journal of the Acoustical Society of Korea
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• v.43 no.4
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• pp.445-454
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• 2024

To detect underwater targets using sonar, sonar performance analysis that reflects the ocean environment and sonar characteristics must be performed. Sonar performance modeling of passive and monostatic sonar can be performed relatively quickly even considering the ocean environment. However, since bistatic and multistatic sonar performance modeling require higher computational complexity and much more time than passive or monostatic sonar cases, they have been performed by simplifying or not considering the ocean environment. In thisstudy, the effects of reverberation and ocean environment in bistatic sonar performance were analyzed using the bistatic reverberation modeling in the Ulleung Basin of the East Sea. As the sonar operation depth approaches the sound channel axis, the influence of the bathymetry on sound propagation is reduced, and the reverberation limited environment is formed only at short distances. Finally, it was confirmed that similar trends appeared through comparison between the simplified and elaborately calculated sonar performance modeling results.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.139-149
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• 2010

Internet was designed for network scalability and best-effort service which makes all hosts connected to Internet to be vulnerable against attack. Many papers have been proposed about attack detection algorithms against the attack using IP spoofing and DoS/DDoS attack. Purpose of DoS/DDoS attack is achieved in short period after the attack begins. Therefore, DoS/DDoS attack should be detected as soon as possible. Attack detection algorithms using false alarm rates consist of the false negative rate and the false positive rate. Moreover, they are important metrics to evaluate the attack detections. In this paper, we analyze the performance of the attack detection algorithms using the impact of false negative rate and false positive rate variation to the normal traffic and the attack traffic by simulations. As the result of this, we find that the number of passed attack packets is in the proportion to the false negative rate and the number of passed normal packets is in the inverse proportion to the false positive rate. We also analyze the limits of attack detection due to the relation between the false negative rate and the false positive rate. Finally, we propose a solution to minimize the limits of attack detection algorithms by defining the network state using the ratio between the number of packets classified as attack packets and the number of packets classified as normal packets. We find the performance of attack detection algorithm is improved by passing the packets classified as attacks.

• The Journal of the Acoustical Society of Korea
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• v.43 no.3
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• pp.305-313
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• 2024

For effective bi-static sonar operation, detection performance analysis must be performed reflecting the characteristics of sound propagation due to the ocean environment and target information. However, previous studies analyzing bistatic sonar detection performance have either not considered the ocean environment and target characteristics or have been conducted using simplified approaches. Therefore, in this study, we compared and analyzed the bistatic detection performance in Yellow sea and Ulleung basin both with and without considering target characteristics. A numerical analysis model was used to derive an accurate bistatic target strength for the submarine-shaped target, and signal excess was calculated by reflecting the simulated target strength. As a result, significant changes in detection performance were observed depending on the source and receiver locations as well as the target strength.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.237-243
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• 2017

In this paper, the detection performance of the electro-optical telescopes which observes and surveils space objects including artificial satellites, is analyzed. To perform the Modeling & Simulation(M&S) based analysis, satellite orbit model, telescope model, and the atmospheric model are constructed and a detection scenario observing the satellite is organized. Based on the organized scenario, pointing accuracy is analyzed according to the Field of View(FOV), which is one of the key factors of the telescope, considering pointing angle command error. In accordance with the preceding result, detection possibility according to the pixel-count of the detector and the FOV of the telescope is analyzed by discerning detection by Signal-to-Noise Ratio(SNR). The result shows that pointing accuracy increases with larger FOV, whereas the detection probability increases with smaller FOV and higher pixel-count. Therefore, major specification of the telescope such as FOV and pixel-count should be determined considering the result of M&S based analysis performed in this paper and the operational circumstances.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.304-306
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• 2012

IDS는 네트워크를 통해 외부에서 들어오는 공격을 감지하고 차단하는 시스템으로 Snort는 대표적으로 널리 이용되고 있는 비상업적 IDS이다. Snort는 서버로 들어오는 패킷과 침입탐지 규칙을 비교하여 네트워크 공격을 탐지한다. 네트워크 공격이 다양해지고 인터넷 사용이 증가하면서 탐지할 대상이 많아졌기 때문에 Snort의 성능을 유지하기 어려워지고 있다. 따라서 소프트웨어적으로 탐지엔진의 알고리즘을 성능을 향상시키거나 하드웨어적으로 패킷처리 능력을 향상시키는 연구가 진행되고 있다. 본 논문에서는 소프트웨어나 하드웨어적인 성능 향상과는 달리 침입탐지 규칙에 기반하여 이를 좀 더 명확하고 효율적으로 정하고 관리하여 Snort의 성능을 향상시키는 접근방법을 제안하였다. 이를 위해 우선적으로 Snort의 침입탐지 규칙에 대해 분석하였고 그 중 개선할 수 있는 Snort 규칙에 대해서 새로운 침입탐지 규칙을 제안을 하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.245-246
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• 2022

최근 IoT 환경에서 기계학습을 이용한 공격 탐지 모델의 연구가 활발히 진행되고 있으며, 탐지 정확도도 점차 향상되고 있다. 하지만, IoT 환경의 특징인 저 사양 하드웨어, 고차원의 특징, 방대한 트래픽 등으로 인해 탐지성능이 저하되는 문제가 있다. 따라서 본 논문에서는 MQTT(Message Queuing Telementry Transport) 프로토콜 기반의 IoT 환경에서 수집된 데이터셋을 대상으로 주성분 분석(Principal Component Analysis)과 LightGBM을 이용하여 데이터셋 차원을 감소시키고, 공격 클래스를 분류하였다. 실험결과 원본 데이터셋 차원을 주성분 3개(약 9%)로 감소시켰음에도 모든 특징(33개)을 사용한 실험결과와 거의 유사한 성능을 보였다. 또한 기존 연구의 특징 선택을 통한 탐지 모델과 비교하였을 때도 분류성능이 더 우수한 것으로 나타났다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.697-699
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• 2003

본 논문은 스트리밍 환경에서 서버의 고장을 빠르게 탐지하기 위해 동적임계점을 사용하고 이에 대한 성능을 분석한다. 제안된 기법은 스트리밍의 특성을 이용하여 질의 전송 시간을 결정하게 되는데 서버의 패킷도착 지연으로 인해 발생되는 질의 전송 시간의 증가를 최소화시키기 위해 패킷 지연도착 시간을 반영하지 않는 알고리즘을 적용하였다. 고장탐지에 대한 성능분석을 위해 스트리밍의 종류에 따라 질의 전송 시간이 다양하게 적용될 수 있기 때문에 다양한 스트리밍 자료를 활용하여 실험하였으며 제안된 기법의 성능을 검증하였다.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.711-718
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• 2004

Packet sampling is the techniques to collect a part of the packets through network and analyze the characteristicsof the traffic for managing the network and keeping security. This paper presents a study on the sampling techniques applied to DDoS traffic and on the characteristics of the sampled traffic to detect DDoS attack efficiently and improve traffic analysis capacity. Three famous sampling techniques are evaluated with different sampling rates on various DDoS traffics. To analyze traffic characteristics, one of the DDoS attack detection method. Traffic Rate Analysis (TRA) is used. Simulation results verify that using sampling techniques preserve the traffic characteristics of DDoS and do not significantly reduce the detection accuracy.