• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.55-63
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• 2011

Space debris is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. Since plenty of spacecrafts were launched in space after 1957, the number of space debris has been increased. According to USSTRATCOM, the number of space debris which are bigger than 10cm is more than 15,000. Recently two critical events were occurred. Which one was that China shot down their satellite using missile and the other was that t o satellite, Iridium 33 and Cosmos 2251, collided in space. Space debris environment in which KOMPSAT-2 is operating has been severe. This paper presents the status of space debris and international activity, and the comparison of conjunction assessment process between Korea Aerospace Research Institute and abroad satellite operation center.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.523-536
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• 2013

A recent air defense missile system is required to have a capability to intercept short-range super-high speed targets such as tactical ballistic missile(TBMs) by performing engagement control efficiently. Since flight time and distance of TBM are very short, the missile defense system should be ready to engage a TBM as soon as it takes an indication of the TBM launch. As a result, it has to predict TBM trajectory accurately with cueing information received from an early warning system, and designate search direction and volume for own radar to detect/track TBM as fast as it can, and also generate necessary engagement information. In addition, it is needed to engage TBM accurately via transmitting tracked TBM position and velocity data to the corresponding intercept missiles. In this paper, we proposed a method to estimate TBM trajectory based on the Kepler's law for the missile system to detect and track TBM using the cueing information received before the TBM arrives the apogee of the ballistic trajectory, and analyzed the bias of prediction error in terms of the transmission period of cueing data between the missile system and the early warning system.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.102-103
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• 2000

화학레이저는 화학연료의 반응에서 생성되는 막대한 화학에너지를 이용하여 레이저를 발생시키며, 반응하는 화학연료의 양에 따라 수천 kW의 고출력을 낼 수 있는 가장 강력한 레이저이다. 화학레이저인 Chemical Oxygen-Iodine Laser(COIL)는 염소기체(Cl$_2$)를 염기성 과산화수소수 용액과 반응시켜 고에너지의 여기산소(O$_2$($^1$$\Delta$))를 생성시키고 여기산소가 다시 요오드 원자와 반응하면서 1.3 $mu extrm{m}$ 파장의 레이저를 발생시킨다.(1)-(2) 이와같은 COIL 레이저는 발진효율이 높고 포화 강도가 높아 수십 kW 급의 고출력이 용이하게 이루어 질 수 있으며 광섬유 전송시 광손실이 가장 적어 레이저 빔의 원격 전송에 의한 재료가공에 적합한 레이저이다. 가공용레이저로 많이 사용하는 $CO_2$ 레이저에 비해 발진 파장이 짧으므로 재료의 광흡수율이 높아 일반 산업분야의 용접/절단에서 기존의 $CO_2$ 레이저를 대체할 것으로 기대되는 상용성이 큰 레이저이다.(3)-(4) 또한 COIL은 우수한 집속 특성을 유지하면서도 고출력의 개발이 가능하다. 이미 외국에서는 비록 단시간 동안 동작하지만 수백 kW급이 실현되었으며 수천 kW 급 고출력 항공기탑재형 COIL 이 수백 km의 거리에서 미사일을 요격하기위해 지금 개발중에 있다.(5) 일반 산업용 광섬유에 의해 쉽게 전송되는 파장인 1.315 $\mu\textrm{m}$ 인 수십 kW 급 COIL 은 조선 등의 중공업산업용 및 원자력 제염/해체분야에서 다용도 기술로서 광범위하게 사용될 것이다. COIL은 다양한 재료와 다양한 두께의 구조물 절단, 표면처리 그리고 용접에도 이용될 수 있다. COIL의 산업화는 빠르게 발전하고 있으며 산업용으로써 장시간 연속사용이 가능한 20-30 kW급 시설이 곧 개발될 것으로 기대된다. 따라서 개발될 고출력 화학레이저가 앞으로 원자력시설의 해체시 작업자의 안전성 향상에 크게 기여할 수 있게 되었다.(6) 여기서는 화학레이저인 COIL 장치와 기본적인 원리, 그리고 염소유량에 따른 출력특성등을 살펴보기로 하겠다. (중략)

• Journal of the Korea Society for Simulation
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• v.27 no.1
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• pp.33-38
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• 2018

This paper introduces the simulation concepts and technical approach of wire-guided torpedo performance analysis simulator, as a consequence, provide a framework for understanding overall attack procedures and effectiveness of tactics to torpedo operator. It described the mathematical models of simulation components and weapon engagement principle, especially it derived the closed-form solution of time consumption and leading angle problem of torpedo attack situation based on geographical assumption. In addition, it adopted the proportional navigation guidance at final stage of torpedo attack and also consider the tradeoff relation between target ship speed(propeller noise level) and detection probability, so that it improves the fidelity of physical realism. Simulator is developed with high degree of freedom in the perspective of tactical situation, and it helps user to understand the overall situation and tactical effectiveness.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.365-372
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• 2021

This paper deals with an optimal Weapon-Target Assignment (WTA) algorithm for Closed-In Weapon Systems (CIWS), considering variable burst time. In this study, the WTA problem for CIWS is formulated based on Mixed Integer Linear Programming (MILP). Unlike the previous study assuming that the burst time is fixed regardless of the engagement range, the proposed method utilizes the variable burst time based on the kill probability according to the engagement range. Thus, the proposed method can reflect a more realistic engagement situation and reduce the reaction time of CIWS against targets, compared to the existing method. In this paper, we first reformulate the existing MILP-based WTA problem to accommodate the variable burst Time. The proposed method is then validated through numerical simulations with the help of a commercial optimization tool.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.508-516
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• 2019

In this paper, we propose a guidance law to control Impact Angle in consideration of look angle limit of the missile with strapdown seeker on the non-maneuvering target. The proposed law is based on sliding mode algorithm and generates acceleration commands using look angle and line of sight information provided by the strapdown seeker and navigation system. And, target velocity and target path angle are provided by like TADS (Target Acquisition and Designation System) at launch time. We can confirm that the target interception and impact angle control are possible through the convergence of the proposed sliding surface. In addition, it is possible to confirm that the sign of derivative result of the look angle at the maximum and minimum look angle is opposite to the sign of the look angle, so the look angle limit is not exceeded.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.89-95
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• 2019

This paper introduces the simulation concepts and technical approach of underwater weapon system performance analysis simulator, especially focused on probabilistic target detection concepts. We calculated the signal excess (SE) value using SONAR equation, then derived the probability density function(PDF) for target presence($H_1$) or absence($H_0$) cases, respectively. With the Neyman-Pearson detector criterion, we got the probability of detection($P_D$) while satisfying the given probability of false alarm($P_{FA}$). At every instance of simulation, target detection is decided in the probabilistic perspective. With the proposed detection implementation, we improved the model fidelity so that it could support the tactical decision during the operation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.6
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• pp.487-497
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• 2019

It is very difficult to detect ballistic missiles because of small cross-sections of the radar and the high maneuverability of the missiles. In addition, it is very difficult to recognize and intercept warheads because of the existence of debris and decoy with similar motion parameters in each flight phase. Therefore, feature vectors based on the maneuver, the micro-motion according to flight phase are needed, and the two types of features must be fused for the efficient recognition of ballistic warhead regardless of the flight phase. In this paper, we introduce feature vectors appropriate for each flight phase and an effective method to fuse them at the feature vector-level and classifier-level. According to the classification simulations using the radar signals predicted by the CAD models, the closer the warhead was to the final destination, the more improved was the classification performance. This was achieved by the classifier-level fusion, regardless of the flight phase in a noisy environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.5
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• pp.407-417
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• 2019

When a free-falling ballistic missile intercepts a maritime target in a sea clutter environment at high grazing angle, detection performance of the ballistic missile's seeker can be rapidly degraded by the effect of sea clutter. To solve this problem, it is necessary to verify the performance of maritime target detection via simulations based on various scenarios. We accomplish this by applying a two-dimensional cell -averaging constant false alarm rate detector to a two-dimensional radar image, which is generated by merging a sea clutter signal at high grazing angle with a maritime target signal corresponding to the signal-to-clutter ratio. Simulation results using a computer-aided design model and commercial numerical electromagnetic solver in various scenarios show that the performance of maritime target detection significantly depends on the grazing and azimuth angles.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.521-528
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• 2021

In order to allocate an appropriate interceptor weapon to an air track for which the threat assessment has been completed, it is necessary to evaluate the suitability of engagement in consideration of the expected point of engagement. In this thesis, a method of calculating the kill probability is proposed according to the position in the engagement space using Bayesian theorem with multivariate attribute information such as relative distance, approach azimuth angle, and altitude of the air track when passing through the engagement space. As a result of the calculation, it was confirmed that the distribution form of the kill probability value for each point in the engagement space follows a multivariate normal distribution based on the optimal predicted intercepting point. It is expected to be applicable to the engagement suitability evaluation of the engagement space.