• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.1
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• pp.33-39
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• 2017

In this paper, an effective feature which is capable of classifying targets among the detections obtained from 2D range-bearing maps generated in active sonar environments is proposed. Most conventional approaches for target classification with the 2D maps have considered magnitude of peak and statistical features of the area surrounding the peak. To improve the classification performance, HOG(Histogram of Gradient) feature, which is popular for their robustness in the image textures analysis is applied. In order to classify the target signal, SVM(Support Vector Machine) method with reduced HOG feature by the PCA(Principal Component Analysis) algorithm is incorporated. The various simulations are conducted with the real clutter signal data and the synthesized target signal data. According to the simulated results, the proposed method considering HOG feature is claimed to be effective when classifying the active sonar target compared to the conventional methods.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.4
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• pp.49-59
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• 2016

Naval combat system developed in-country is progressing at an alarming rate since 2000. ROK navy will be achieved all vessels that have combat system in the near future. The importance of System Engineering and Integrated Logistics Support based on reliability analysis is increasing. However, reliability analysis that everyone trusted and recognized is not enough and applied practically for development of Defense Acquisition Program. In particular, Existing Reliability Analysis is focusing on reliability index (Mean Time Between Failure (MTBF) etc.) for policy decision of defense improvement project. Most of the weapon system acquisition process applying in the exponential distribution simply persist unreality due to memoryless property. Critical failures are more important than simple faults to ship's operator. There are no confirmed cases of reliability analysis involved with critical failure that naval ship scheduler and operator concerned sensitively. Therefore, this study is focusing on Mean Time To Critical Failure (MTTCF), reliability on specific time and Operational Readiness Float (ORF) requirements related to critical failure of Patrol Killer Guided missile (PKG) combat system that is beginning of naval combat system developed in-country. Methods of analysis is applied parametric and non-parametric statistical techniques. It is compared to the estimates and proposed applications. The result of study shows that parametric and non-parametric estimators should be applied differently depending on purpose of utilization based on test of normality. For the first time, this study is offering Reliability of ROK Naval combat system to stakeholders involved with defense improvement project. Decision makers of defense improvement project have to active support and effort in this area for improvement of System Engineering.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.98-104
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• 2016

This research describes the functional requirements of anti-ship ballistic missile (ASBM) defense systems, which depend on the threat characteristics of the ASBM. Recently, China has carried out a training launch of the DF-21D strategic countermeasures for the placement of Korean terminal high-altitude air defense (THAAD). The ASBM is being used as a primary means of attacking aircraft carriers, using an anti-access/area denial (A2/AD) strategy. Considering the missile technology connection between China and North Korea, there is a very high probability that North Korea already owns an ASBM. From this point of view, work with Aegis operational concepts provided implications for an ASBM threat. Utilizing quality function deployment (QFD) based on the operational concepts, the functional requirement were calculated.

• Journal of the Korean Society of Food Culture
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• v.35 no.3
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• pp.285-293
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• 2020

This study was conducted to monitor the residual pesticides on red pepper powder produced in five regions, which are the major producers of red pepper in Korea, such as Ham-pyeong, An-dong, Yeong-yang, Yeong-gwang, and Cheongyang from 2015 to 2016. Residual pesticides were detected on all samples. Among the 286 pesticides tested, 58 pesticides were detected, with the most frequently detected being chlorfenapyr (93.7%). Twelve types of pesticides (chlorfenapyr, cypermethrin, chlorpyrifos, pyraclostrobin, cyhalothrin, tebuconazole, bifenthrin, deltamethrin, fenvalerate, lufenuron, azoxystrobin, and indoxacarb) were detected in all regions, and 14 types of pesticides were used only in certain regions. An analysis of the residual pesticides showed that none of the pesticides detected exceeded the MRL (Maximum Residue Limits). The Positive List System (PLS) requirements were applied to eight pesticides that had no set MRLs. 0.01 mg/kg (PLS requirements) was exceeded in 12 cases. A comparison of the estimated daily intake (EDI) of pesticides with the acceptable daily intake (ADI) to access their risk revealed %ADI values of 0.001-0.756. Carbofuran showed the highest (0.756%), but most pesticides were below 1%. The results show that residual pesticides in red pepper powder are at safe levels.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.223-234
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• 2014

This paper describes the analysis results of channel characteristics in the operating area of satellite OTM(On-The-Move) terminal. The communication channel between the Koreasat-5 and OTM terminal on a test car is measured and recorded from Daejeon to Daecheon, using the downlink frequency of around 20 GHz. And the measurement data are divided into two classes ; highway environment and national road environment, and then are statistically analyzed. The statistical evaluation of satellite channel is conducted by using probability density function and Markov model and then presents average connection duration(ACD), average fade duration( AFD), and level crossing rate(LCR) of highway environment and national road environment. Finally the statistics data of the two environments are compared with each other.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.11-19
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• 2013

An experimental study was conducted to investigate fuel injection characteristics through swirl injectors when the fuel was heated to very high temperature conditions. Three swirl injectors with different orifice diameters and swirler geometries were used to measure the flow coefficient (${\alpha}$) for the injection pressure ranges between 3 and 10 bar and the fuel temperature from 50 to $270^{\circ}C$. The results showed that the variation characteristics of ${\alpha}$ with respect to cavitation number ($K_c$) were highly dependent on both the orifice diameter and the swirler geometry. In addition, the characteristics of ${\alpha}$ variation with respect to AR, the area ratio of the flow through the swirler and the orifice, has revealed that the effect of boiling is retarded but the slope of decreasing ${\alpha}$ after the boiling effect is present tumbles as AR increases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.299-311
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• 2011

In this paper, we have identified the system instability factors in a bistatic radar system using pulse chasing and considered their effects on the bistatic receiver's MTI(Moving Target Indication) improvement performance. The pulse chasing is a scan method that searchs a restricted area on the transmit pulse-to-pulse basis and the MTI filter is a signal processing that separates a target from some kinds of interferences such as clutter using small number of transmit pulses. Ideal MTI processing performance, e.g., clutter attenuation and improvement, has been limited by the property of the clutter itself, however, the MTI performance in a proposed bistatic receiver configuration could be affected by the receiving beam pointing error during pulse chasing scanning. Also, for the bistatic receiver, we have defined other system instability factors, which result from the time synchronization error, COHO's phase error, the frequency/phase synchronization error, and have analyzed their effects on the system performance improvement.

• Journal of the Korea Society of Computer and Information
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• v.28 no.8
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• pp.119-126
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• 2023

In this paper, a new model was presented to objectively evaluate the defense ability of defenders in Korean professional baseball. In the proposed model, using Korean professional baseball game data from 2016 to 2019, a representative defender was selected for each team and defensive position to evaluate defensive ability. In order to evaluate the defense ability, a method of calculating the defense range for each position and dividing the calculated defense area was proposed. The defensive range for each position was calculated using the Convex Hull algorithm based on the point at which the defenders in the same position threw out the ball. The out conversion score and victory contribution score for both infielders and outfielders were calculated as basic scores using the defensive range for each position. In addition, double kill points for infielders and extra base points for outfielders were calculated separately and added together.

• Journal of Advanced Navigation Technology
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• v.18 no.4
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• pp.260-267
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• 2014

For the purpose of improving the accuracy of Wide Area Differential GNSS (WA-DGNSS), estimation performance of ionospheric delay error which has a great impact on GPS error sources should be enhanced. This paper applied multi-constellation GNSS which represents GPS in USA, GLONASS in Russia, and Galileo in Europe to WA-DGNSS algorithm in order to improve performance of ionospheric delay estimation. Furthermore, we conducted simulation to analyze ionospheric delay estimation performance in Korean region by increasing the number of reference stations. Consequently, using multi-constellation GNSS to improve performance of ionospheric delay estimation is more effective than increasing the number of reference stations in spite of similar number of measurements which are in use for estimation. We expect this result can contribute to improvement for ionospheric delay estimation performance of single-frequency SBAS (Satellite Based Augmentation System) user.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.2
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• pp.225-234
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• 2018

In this paper, we consider a problem of partitioning a search area into smaller rectangular regions, so that multiple platforms can conduct search operations independently without requiring unnecessary coordination among themselves. The search area consists of cells where each cell has some prior information regarding the probability of target existence. The detection probability in particular cell is evaluated by multiplying the observation probability of the platform and the target existence probability in that cell. The total detection probability within the search area is defined as the cumulative detection probability for each cell. However, since this search area partitioning problem is NP-Hard, we decompose the problem into three sequential phases to solve this computationally intractable problem. Additionally, we discuss a special case of this problem, which can provide an optimal analytic solution. We also examine the performance of the proposed approach by comparing our results with the optimal analytic solution.