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조창봉 한국군사과학기술학회 2004 한국군사과학기술학회지 Vol.7 No.1
Recently, ship acoustics takes more important role in acoustic stealth and classification of underwater targets. In this paper, a theoretical concept is proposed for M&S-based test and evaluation of ship acoustics. The concept is based on two different approaches: on Top-Down method which emphasizes the survivability of the ship and on Bottom-Up method which considers acoustic characteristics of the ship-equipments. In order to improve the effectiveness of M&S-based T&E for ship acoustics, it is recommended in this paper to compromise the two approaches as adequate.
한반도 근해의 상대적 위치에너지 편차 변화를 이용한 성층화의 특성과 계절별 변화에 대한 연구
조창봉,김영규,장경일,Cho, Chang-Bong,Kim, Young-Gyu,Chang, Kyung-Il 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.2
In this paper, we have proposed a method for quantization of the stratification strength in the sea water and analysing the distributions of the maximum stratification depths calculated by the method at the seas near the Korean peninsular. For calculating the stratification strength, modified and applied the potential energy anomaly formular which was suggested by Simpson in 1977. The data had been collected by NFRDI from 1971 to 2008 were used to determine the maximum vertical density gradient depth and the relative potential energy anomaly at that depth. In the East Sea, the stratification depth has become deepened about 20m in February and April since 1971. In Yellow-South Sea, the maximum density gradient depth has been deepened about 10m only in December during the same period and the difference of the stratification depth between summer and winter has been enlarged. These trends of variation of stratification strength and depth near the Korean peninsular should be investigated more carefully and continuously. And the results of these studies could be adopted for the more efficient operation of underwater weapon and detection systems.
조창봉,이상국,도경철,Cho, Chang-Bong,Lee, Sang-Guk,Dho, Kyeong-Cheol 한국군사과학기술학회 2009 한국군사과학기술학회지 Vol.12 No.5
In this paper, we have proposed a design for security network system passing through the non-security network which is commonly used for various networking services. Based on the security requirements which are assumed that the large classified data are bi-transmitted between a server and several terminals remotely located, some application methods of security techniques are suggested such as the network separation technique, the scale-down application technique of certification management system based on the PKI(Public Key Infrastructure), the double encryption application using the crypto-equipment and the asymmetric keys encryption algorithm, unrecoverable data deleting technique and system access control using USB device. It is expected that the application of this design technique for the security network causes to increase the efficiency of the existing network facilities and reduce the cost for developing and maintaining of new and traditional network security systems.
동해에서 난수성 소용돌이의 원거리 음파전달에 미치는 영향
김원기,조창봉,박정수,한주영,나영남,Kim, Won-Ki,Cho, Chang-bong,Park, Joung-Soo,Hahan, Jooyoung,Na, Youngnam 한국음향학회 2015 韓國音響學會誌 Vol.34 No.6
동해에는 주변 수온보다 온도가 높은 난수성 소용돌이가 자주 발생되는 것으로 알려져 있다. 이러한 난수성 소용돌이의 발생은 음속구조의 변화를 야기해 음전달특성을 변화시키게 되며, 특히 원거리 음전달에 큰 영향을 줄 것으로 예상된다. 본 논문에서는 난수성 소용돌이가 확인되는 2007년 3월 23일의 수온자료를 재분석한 자료를 이용하여 난수성 소용돌이가 원거리 음전달에 미치는 영향을 분석하였다. 연구를 위해 포물선 방정식 모델을 이용해 음파 전달손실과 평균 직접 신호초과 거리를 이용한 탐지거리 성능분포분석을 수행하였다. 분석결과 난수성 소용돌이의 존재는 난수성 소용돌이가 존재하지 않을 때와는 매우 다른 음전달 특성을 보여주고 있으며, 특히 난수성 소용돌이의 경계는 음전달의 제한적인 요소가 될 수 있기 때문에 원거리 음전달에 불리할 것으로 판단된다. 이러한 난수성 소용돌이에 의한 원거리 음전달의 제한은 해저 심도가 낮을수록 더 커지는 것을 확인하였다. It is well known that warm eddy is frequently developed through the year in the East Sea. The warm eddy may affect sound propagation due to changes of sound velocity structures in the sea water. To verify the effects of the warm eddy for long-range sound propagation, transmission loss and performance surface, which were used mean direct signal excess range generated by sound propagation modeling using re-analyzed climatology data on March 23th in 2007 were analysed. From these analyses, we found that characteristics of sound propagation in the sea water are changed by the warm eddy, and boundaries of the warm eddy act as a barrier for long-range sound propagation. Furthermore, these disadvantages of the eddy related to sound propagation were increased when the sea bottom depth is shallow.
나영남,조창봉,손수욱,한주영 한국음향학회 2024 韓國音響學會誌 Vol.43 No.1
For measuring the performance of passive sonars, we usually consider the maximum Detection Range (DR) under the environment and system parameters in operation. In shallow water, where sound waves inevitably interacts with sea surface or bottom, detection generally maintains up to the maximum range. In deep water, however, sound waves may not interact with sea surface or/and bottom, and thus there may exist shadow zones where sound waves can hardly reach. In this situation, DR alone may not completely define the performance of each sonar. For complete description of sonar performance, we employ the concept ‘Robustness Of Detection (ROD)’. In the coastal region of the East Sea, the spatial variations of water masses have close relations with DR and ROD, where the two parameters show reverse spatial variations in general. The spatial and temporal analysis of the temperature by employing the Empirical Orthogonal Function (EOF) shows that the 1-st mode represents typical pattern of seasonal variation and the 2-nd mode represents strength variations of mixed layers and currents. The two modes are estimated to explain about 92 % of the variations. Assuming two types of targets located at the depths of 5 m (shallow) and 100 m (deep), the passive sonar performance (DR) gives high negative correlations (about -0.9) with the first two modes. Most of temporal variations of temperature occur from the surface up to 200 m in the water column so that when we assume a target at 100 m, we can expect detection performance of little seasonal variations with passive sonars below 100 m.
변상신,조창봉 한국음향학회 2022 韓國音響學會誌 Vol.41 No.6
2007년 8월 동해 연안에서 연안용승 현상이 발생 되었고, 이에 따른 수직적인 수온과 염분 자료가 실시간 해양관측부이를 통해 획득되었다. 시계열 관측자료를 기반으로 연안용승 발생 전·중·후의 수직적인 음속구조를 산출하였고, 연안용승의 수평적인 규모와 실제 해저지형 등을 고려한 음향모델링을 통해 연안용승이 수중의 음파 전달과 탐지환경에 어떠한 영향을 미치는지 분석하였다. 포물선 방정식 모델을 이용한 저주파(500 Hz) 음파 전달손실과 심도별 표적 탐지거리를 비교·분석한 결과, 동해 연안에서 용승이 발생하면 그렇지 않은 일반적인 음탐환경에 비해 최대 약 10 dB의 탐지이득을 기대할 수 있는 것으로 분석되었다. 또한, 이번 연구를 통해 용승 전·후 약 2 ~ 3일의 짧은 기간 내에서도 음파전달 특성이 크게 달라질 수 있음을 확인하였다.