• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.1
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• pp.55-64
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• 2023

Gas turbine engines are widely used as prime movers of generator and propulsion system in warships. This study addresses the problem of designing a DS-based PID controller for speed control of the LM-2500 gas turbine engine used for propulsion in warships. To this end, we first derive a dynamic model of the LM-2500 using actual sea trail data. Next, the PRC (process reaction curve) method is used to approximate the first-order plus time delay (FOPTD) model, and the DS-based PID controller design technique is proposed according to approximation of the time delay term. The proposed controller conducts set-point tracking simulation using MATLAB (2016b), and evaluates and compares the performance index with the existing control methods. As a result of simulation at each operating point, the proposed controller showed the smallest in %OS, which means that the rpm does not change rapidly. In addition, IAE and IAC were also the smallest, showing the best result in error performance and controller effort.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.1
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• pp.137-147
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• 2017

Wartime warship damage rate indicates how much damage of friend warships shall have occurred during naval battles accomplished under specific war operational plans. The wartime damage rate analysis provides the baseline of wartime resources requirements. If wartime damage rate is overestimated, the national finance will get to negative effects because of exceeding the budget for inventory, operation, and maintenance of resources. Otherwise, if wartime damage rate is underestimated, the national defense will lose in the war because of lack of critical resources. In this respect, it is important to estimate the wartime damage rate accurately and reasonably. This paper proposes a systematic procedure to estimate the wartime warship damage rate. The procedure consists of five steps; force analysis, operation plan analysis, input variable definition, simulation modeling, and output analysis. Since the combat simulation model is regarded as the main tool to estimate damage rate, the procedure is focused on the development of model and experiments using the model. A case study with virtual data is performed to demonstrate the effectiveness of the developed procedure.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.733-743
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• 2014

Since the technology of anti-ship missiles has advanced rapidly, defending battleships from the threat of anti-ship missiles is a crucial factor for the survival of warships. In this paper, we analyze the performance of an anti-ship missile defense system whose name is Close-In-Weapon-System. We show the survival probability of a warship equipped with the Close-In-Weapon-System as the number of anti-ship missiles attacking the warship varies. Because of the complex and dynamic operational characteristics surrounding the Close-In-Weapon-System such as speed of missiles, different range of an individual weapon in the weapon system, and the continuous change of the kill probability of the missiles corresponding to the distance of missiles from ships, few work has been done for the performance of Close-In-Weapon-System. We present a model to incorporate all the dynamic characteristics of the system using absorbing Markov Chain. With our results, we expect commanders of warships equipped with Close-In-Weapon-System to be provided with more helpful information on how to deal with the anti-ship missiles.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.579-581
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• 2015

Air threat such as aircrafts or missiles were incresed rapidly after World War II, warships were relatively vulnerable to air threat. Therefore U.S. and allies developed various Tactical Data Link(TDL) to defend warships from air threat. Target information can be managed and shared with other station by real or near-real time due to TDL. TDL is base system to manage battlefield and to carry out C2(Command and Control) effectively and rapidly. In this paper, the type, current operating status and characteristic of TDL is surveyed and newest technical trend such as LINK-K is described.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.6
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• pp.53-59
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• 2021

The ROK Navy operates many war ships despite its short history. Various types of war ships, such as submarines, destroyers, frigates, corvette etc., use suitable propulsion systems for the operational requirements of each war ship. A hybrid propulsion system was introduced to change from the current mechanical propulsion system to an electric propulsion system according to the changing patterns of naval warfare, and it is expected that an integrated electric propulsion system will also be introduced. Therefore, this paper investigates the propulsion system of major ships operated by the Korean Navy, predicts the changes in future naval warfare, and proposes a propulsion system for future ships.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1422-1432
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• 2011

Recently, wireless network has been playing an important role in communication system and the applications have become wider with its big technological leap. In defence sector, there are some attempts to use wireless networks to go beyond the wire system. Especially, most internal space of the warships have the wired communication system, which are complicated and inefficient. In this paper, we measure and make a channel model about the internal parts of the warship which contain compartments and corridors including many differences from general indoor environment for establishing wireless networks in warship's internal space. In the unique environment made of metal, we measure 2.4GHz signals using continuous wave(CW) and analysis the environment to present indoor path-loss model for comparing with results from the ray-tracing tool. Moreover, we draw the conclusion that the environment of warships has a wide difference from conventional environments and put the results to practical use in warship's internal space.

• Journal of Navigation and Port Research
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• v.41 no.5
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• pp.269-276
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• 2017

"Tracking" here refers to the estimation of a moving object with some degree of accuracy where at least one measurement is given. The measurement, which is the sensor-obtained output, contains systemic errors and errors that are due to the surrounding environment. Tracking filters play the key role of the target-state estimation after the updating of the tracking system; therefore, the type of filter that is used for the conduction of the estimations is crucial in the determining of the reliability of the updated value, and this is especially true since the performances of different filters vary when they are subjected to different environmental and initial conditions. The purpose of this paper is the conduction of a comparison between the performances of the ${\alpha}-{\beta}-{\gamma}$ filter and the Kalman filter regarding an ARPA-system tracking module that is used on board high-dynamic warships. The comparison is based on the capability of each filter to reduce noise and maintain a stable response. The residual error is computed from the difference between the true and predicted positions and the true and estimated positions for the given sample. The results indicate that the tracking accuracy of the Kalman filter is higher compared with that of the optimal ${\alpha}-{\beta}-{\gamma}$ filter; however, the response of the optimal ${\alpha}-{\beta}-{\gamma}$ filter is more stable.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.4
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• pp.218-228
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• 2023

Maintaining sea superiority through successful mission accomplishments of warships is being proved to be an important factor of winning a war, as in the Ukraine-Russia war. in order to ensure the ability of a warship to perform its duties, the survivability of the warship must be strengthened. In particular, among the survivability factors, vulnerability is closely related to a damage assessment, and these vulnerability data are used as basic data to measure the mission capability. The warship's mission capability is usually measured using a wargame model, but only the operational effects of a macroscopic view are measured with a theater level resolution. In order to analyze the effectiveness and efficiency of a weapon system in the context of advanced weapon systems and equipments, a warship's mission capability must be measured at the engagement level resolution. To this end, not the relationship between the displacement tonnage and the weight of warheads applied in the theater level model, but an engagement level resolution vulnerability assessment method that can specify physical and functional damage at the hit position should be applied. This study proposes a method of measuring a warship's mission capability by applying the warship vulnerability assessment method to the naval engagement level analysis model. The result can be used as basic data in developing engagement algorithms for effective and efficient operation tactics to be implemented from a single unit weapon system to multiple warships.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.233-237
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• 2014

According to advance of radar technology and increase of air threat, 3D surveillance radars are preferred as shipboard equipments to shorten reaction time. In this paper, reaction time against air target was calculated by simulation in each case, 2D and 3D surveillance radar and it was suggested that a few parameters including purpose of warships, performance of shipboard equipments, threat of surrounding countries and budget to select the reasonable type of radar.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.5
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• pp.714-721
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• 2018

This study proposes a risk evaluation method based on RAM and AHP data in order to prevent subjectivity of risk assessment. The risk assessment consist of Risk Likelihood(RL) and Risk Consequence(RC) in five levels. However, risk analysis of warships is hard to make a judgment because of small quantity production(Ship), long building period, equipment changes, complexity, various kinds of equipments, etc. The proposed RAM data and AHP analysis method are used to quantify each level quantitatively. RAM(MTBF) date is used to classify the RL, and AHP analysis is used to classify the RC. These scientific and data-based method will increase objectivity as well as efficiency of risk evaluation.