• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.1
• /
• pp.22-29
• /
• 2016

Many studies in detection and classification of the targets in the underwater environments have been conducted for military purposes, as well as for non-military purpose. Due to the complicated characteristics of underwater acoustic signal reflecting multipath environments and spatio-temporal varying characteristics, active sonar target detection technique has been considered as a difficult technique. In this paper, we describe the basic concept of Fractional Fourier transform and optimal transform order. Then we analyze the relationship between time-frequency characteristics of an LFM signal and its spectrum using Fractional Fourier transform. Based on the analysis results, we present active sonar target detection method. To verify the performance of proposed methods, we compared the results with conventional FFT-based matched filter. The experimental results demonstrate the superiority of the proposed method compared to the conventional method in the aspect of AUC(Area Under the ROC Curve).

• KIISE Transactions on Computing Practices
• /
• v.21 no.12
• /
• pp.745-750
• /
• 2015

LiDAR(Light Detection and Ranging) technology provides realistic 3-dimension image information, and it has been widely utilized in various fields. However, the utilization of this technology in the military domain requires prompt responses to dynamically changing tactical environment and is therefore limited since LiDAR technology requires complex processing in order for extensive amounts of LiDAR data to be utilized. In this paper, we introduce an Unmanned Aircraft Platform Based Real-time LiDAR Data Processing Architecture that can provide real-time detection information by parallel processing and off-loading between the UAV processing and high-performance data processing areas. We also conducted experiments to verify the feasibility of our proposed architecture. Processing with ARM cluster similar to the UAV platform processing area results in similar or better performance when compared to the current method. We determined that our proposed architecture can be utilized in the military domain for tactical and combat purposes such as unmanned monitoring system.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.21 no.4
• /
• pp.447-455
• /
• 2018

If a hidden enemy is shooting, there is a threat against soldiers in recent conflicts. This paper aims to improve the localization of a muzzle using microphone array. Gunshot noise can provide information about the location of muzzle with two signals, the muzzle blast from the gun barrel and the projectile sound from the bullet. Two signals arrive to the microphone array with different arrival time and angle. If the arrival angles of the two signals are estimated, distance between sniper location and the microphone array can be calculated by using geometric principles. This method was established in 2003 by Pare. But this method has a limitation that it cannot calculate the distance when the arrival angles of the two signals are same. Also it has an error when the angle difference of arrival is small. In order to overcome this limitation, a new method is proposed that uses the change of characteristic of the projectile sound with respect to vertical distance from the trajectory. The proposed method estimates the distance correctly when the arrival angle of two signals are same, and when the angle difference between two signals is increased, the estimation error increases with respect to the angle. Therefore these two methods can be selected according to the angle difference between two signals to estimate the distance of the muzzle. Below the threshold of the angle difference, the proposed method can be used to estimate distance with smaller error than the existing method. This was demonstrated by shooting tests using actual sniper rifles.

• 한국ITS학회:학술대회논문집
• /
• v.2007 no.10
• /
• pp.225-229
• /
• 2007

Recently, wireless sensor networks are deployed in various applications range from simple environment monitoring systems to complex systems, which generate large amount of information, like motion monitoring, military, and telematics systems. Although wireless sensor network nodes are operated with low-power 8bit processor to execute simple tasks like environment monitoring, the nodes in these complex systems have to execute more difficult tasks. Generally, MAC protocols for wireless sensor networks attempt to reduce the energy consumption using duty cycling mechanism which means the nodes periodically sleep and wake. However, in the duty cycling mechanism. a node should wait until the target node wakes and the sleep latency increases as the number of hops increases. This sleep latency can be serious problem in complex and sensitive systems which require high speed data transfer like military, wing of airplane, and telematics. In this paper, we propose a solution for reducing transmission latency through distributed duty cycling (DDC) in wireless sensor networks. The proposed algorithm is evaluated with real-deployment experiments using CC2420DBK and the experiment results show that the DDC algorithm reduces the transmission latency significantly and reduces also the energy consumption.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.4
• /
• pp.137-144
• /
• 2006

The basic data obtained in this research for single element performance were directly applied to the design of injector head(7 elements). Designed performance of the 7-element Swirl Coaxial injector was $245kg_f$ sea level thrust with 20bar combustion chamber pressure. Numerical analysis were performed to obtain the change of spray pattern for the design of injector head, and we confirmed the feasibility and application of those results. Hot tests were performed for the multi-element injector to compare with the performance of the single element injector and those can be applied to the design of scaled liquid rocket engine. The basic data obtained in this research can be directly applied to the real liquid rocket injector design.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.2
• /
• pp.243-251
• /
• 2010

The military has been putting great efforts into applying data communication on existing voice communication systems being used in NCW(Network Centric Warfare). Data communication will be an effective choice in one of many effort to yield a minimum kill chain, comparing to legacy voice communications, when tactical units conduct their missions. However, the required budget will be enormous, in case of the replacement of a lot of legacy communication systems with new one. As a cost-effective alternative, the tactical data communication systems using the conventional radio systems instead of the development of new radio systems has been proposed. It is mandatory, though, to ensure QoS while maintaining data communication by making use of legacy radio systems already in use. This paper focuses on the performance issues experimented and analyzed for tactical data communication through the legacy radio systems as the first step towards guaranteed QoS. We have conducted various experiments such as the transmission error rate on certain tactical messages, performance evaluation of redundant transfers, the relationship between the transmission frame size and rate of error, the identification of error points in the transmission frame, and techniques to reduce the errors in both hopping and non-hopping modes. As a result of the performance experiments, The adaptive communication module which decides the redundant transmission or the Forward Error Correction(FEC) technique by analyzing channel status and current transmission status(hopping/non-hopping) of the legacy radio should be designed. the FEC technique in non-hopping, and the redundant transmission technique in hopping mode was recommended from the result of experiment with the frame size is 20bytes in non-hopping and 10Bytes frame size in hopping mode.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.20 no.3
• /
• pp.454-466
• /
• 2017

North Korea intended to increase the power of its nuclear weapons and standardize warhead to be loaded in ballistic missiles through the $4^{th}$ and $5^{th}$ nuclear tests. In this study, three kinds of nuclear weapons that North Korea might have used in the $4^{th}$ and $5^{th}$ nuclear tests to achieve their technical goals were suggested. Monte Carlo modeling and various technical assessments have shown that boosted fission weapons are most likely to be used. Also, using the empirical formula considering the burial depth of explosion, we found that the yield of the $4^{th}$ and $5^{th}$ nuclear tests is at least twice as strong as that is expected it could be and the initial design power could reach 8kt before amplification. This means that North Korea has already achieved a substantial level of nuclear fusion technology through the $4^{th}$ test and has made a breakthrough in the miniaturization of nuclear weapons through the $5^{th}$ test. After two or three additional tests, North Korea is expected to have nuclear missiles equipped with nuclear warhead by 2020, which is expected to complete ballistic missile development.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.3
• /
• pp.423-431
• /
• 2011

Warfighting experimentation is an important process for identifying requirements against changing military environment and for verifying proposed measures for reforming military service. The wargame simulation experiment is regarded as one of the most effective means to warfighting experimentation, and its importance is increasing than ever. On the other hand, the results of wargame experiments could be unreliable due to the uncertainty involved in the experimental procedure. To improve the reliability of the experimental results, systematic experimental procedures and analysis methods must be employed, and the design and analysis of experiments technique can be used effectively for this purpose. In this paper, AWAM, a wargame simulator, is used to optimize the organization of operational troops. The simulation model describes a warfighting situation in which the 'survival rate of our force' and the 'survival rate of the enemy force' are considered as responses, 'the numbers of weapons in the squad' as control factors, and 'the uncontrollable variables of the battlefield' as noise factors. In addition, for the purpose of effective experimentation, the product array approach in which the inner and outer orthogonal arrays are crossed is adopted. Then, the signal-to-noise-ratio for each response and the desirabilities for the means and standard deviations of responses are calculated and used to determine a compromise optimal solution. The experimental procedures and analysis methods developed in this paper can provide guidelines for designing and analyzing wargame simulation experiments for similar warfighting situations.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.2
• /
• pp.208-214
• /
• 2012

The spectral radiance received by a remote sensor is consisted of the self-emitted component directly from the target surface, the reflected component of the solar irradiance at the target surface, and the scattered component by the atmosphere without ever reaching the object surface. In general, the self-emitted component is the most important part in the infrared signatures from the target. We measured the solar irradiation, sky irradiation, air temperature, wind velocity, wind direction, relative humidity, and atmospheric pressure together with the surface temperatures of rectangular parallelepiped targets. The measured diurnal surface temperature variations on the three different rectangular parallelepiped targets constructed by the steel, aluminum and bakelite are obtained at the same time intervals. The measured surface temperature results show that the top surface temperature of bakelite recorded up tp $7.6^{\circ}C$ higher than that of aluminium and $6.1^{\circ}C$ higher than that of steel at 11 AM on the sunny condition. A complete set of measured data including the surface temperature of rectangular parallelepiped targets together with the detailed weather information can be a valuable reference for future study.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.19 no.2
• /
• pp.195-201
• /
• 2016

An experimental study has been found the air guide grooves for reducing drag. When a bullet is fired and move in the air, the drag is generated. The vortex which is one of the types of drag hinders the movement of the bullet. To solve this phenomenon, cut a negative grooves that we are called the air guiding grooves at the back of bullet. The grooves bullet has identified that the drag compared to conventional ammunition(KM80 and K193) is reduced to 4.480 and 4.054 : 10 % through a Finite Analysis Program($Ansys^{TM}$). Even pressure center was retreating 0.72 % compared to a Bullet(KM80 and K193). Effect obtained with these results is the accuracy of the grooves bullet in a shooting test was improved by over 32 %(KM80: 2.86, air guide grooves : 1.94) compared to conventional ammunition(KM80 and K193). In addition, muzzle velocity is increased 73 m/s. This is expected to be extended the velocity and effective range of bullet. Also, the velocity of the grooves bullet is increased when moving in the air while the velocity of the bullet(KM80 and K193) is reduced. The gas ejected from the muzzle to be balanced and stable flight of the Bullet. Given these effects, we can reckon the air guide grooves have positive influence.