• Journal of the Korea Society of Computer and Information
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• v.28 no.4
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• pp.93-104
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• 2023

Recently, the technology of drones is developing remarkably. The role of military drones is so great that they can cause serious damage to the enemy's important strategic assets without any damage to our allies in all battlefield environments (land, sea, air). However, the battleship combat management system currently operated by the Korean Navy is vulnerable to defense because there is no customized defense system against drones. As drones continue to develop, they are bound to pose a major threat to navy in the future. This paper proposes a way for the warfare software of naval combat management system sets a combat mode suitable for anti-drone battle, evaluates the threat priority in order to preemptively respond to drone threats and eliminate drone threats through automatic allocation of self-ship-mounted weapons and sensors, and through a test of the improved warfare software in a simulated environment, it was proved that the time to respond to the drone was improved by 62%.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.510-516
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• 2013

This paper suggests a 3-phase series-resonant type high voltage capacitor charger for an EML pulsed power system. The operating principle on the charger is explained by an equivalent circuit. Additionally, we analyze the charging characteristic in one discontinuous conduction mode and three continuous conduction modes. The analysis shows that the resonant current per phase is two thirds of the 3-phase charger's average charging current and one third of the single-phase charger's average charging current with the same capacity. We suggest a design method of the 3-phase capacitor charger in each operational mode and present an example of 3.5 kW capacitor charger at ${\omega}_s=0.33{\omega}_r$. The 3.5 kW 3-phase capacitor charger prototype is assembled with a TI28335 controller and a 40 kJ, 7 kV capacitor. The design rules based on the analysis are verified by experiment.

• International Journal of Automotive Technology
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• v.8 no.2
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• pp.211-217
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• 2007

The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS (Anti-lock Brake System) systems. In realizing the wheel slip control systems, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance and stability enhancement. In this paper, a robust wheel slip controller is developed based on the adaptive sliding mode control method and an optimal target slip assignment algorithm is proposed for maximizing the braking force. An adaptive law is formulated to estimate the braking force in real-time. The wheel slip controller is designed based on the Lyapunov stability theory considering the error bounds in estimating the braking force and the brake disk-pad friction coefficient. The target slip assignment algorithm searches for the optimal target slip value based on the estimated braking force. The performance of the proposed wheel slip control system is verified in HILS (Hardware-In-the-Loop Simulator) experiments and demonstrates the effectiveness of the wheel slip control in various road conditions.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.92-96
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• 2003

This paper deals with the characteristics of persistent current switch (rCS) system fer applied HTS magnet system. To apply the high-Tc superconductor in superconducting machine such as motror, generator, MAGLEV, MRI, and NMR, the study on high-Tc superconducting persistent current mode must be performed. In this experiment, the PCS system consists otd superconducting magnet, PCS and magnet power supply. The superconducting magnet was fabricated by connecting four double pancake coils (DPCs) in series. The PCS was inductive double pancake coil type and heated up by the SUS 303L tape heater. The optimal length of PCS was calculated and thermal quench state of PCS was simulated by using finite element method(FEM) and compared with experimental results. The optimal energy to normalize the PCS was calculated and introduced. Finally, the persistent current was observed with respect to various ramping up rate and magnitude of charging current.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.938-945
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• 2003

In the present study, the inverse perturbation method is applied to the structural damage detection in conjunction with a system condensation technique. The system condensation technique is adopted to r esolve the problem due to the incomplete measurement of the degrees-of-freedom (DOFs) in a natural mode. However, the numerical difficulty may arise in the system condensation when the DOFs to be measured are not properly selected. Thus, the issue of sensor placement for structural damage detection, in the framework of the condensation technique-based inverse perturbation method, is considered in this study. Also, a methodology to measure the number of sensors required to obtain reliable damage detection is proposed and then verified through some illustrative example problem.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.43-45
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• 2007

We developed a portable urodynamics monitoring system using personal digital assistance (PDA) and proposed a new method for measuring the abdominal pressure in non invasive mode using surface EMG signals. This system is consisted of a signal conditioning and control module and could measure the vesical, abdominal and detrusor pressure. The result showed a high correlation coefficient between the practical abdominal pressure, using a conventional rectal catheter and the estimated values, by our proposed algorithm (r=0.81). This system should prove a useful tool in the future evaluations of ambulatory urodynamics monitoring study.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.573-579
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• 2015

A control algorithm of thyristor dual converter power system is proposed in this study for a railway power substation. The thyristor dual converter can use regenerative power without an additional system using control algorithm. An autonomous voltage and mode change method is also proposed to provide uninterrupted power to the railway. A 10 kW reduced model of the thyristor dual converter power system is built and tested to verify the validity of the proposed control algorithm.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.125-128
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• 2005

This paper illustrates potential applications of POM/OPM/BOR, which are used for deterministic reliability evaluation in the operation mode (operational planning and operating) in Korea Power System. Deterministic reliability evaluation in this paper bases the philosophy of the marginality and the limitation of physical quantity (voltage and thermal in main) under contingency analysis. The POM/OPM/BOR tools have been developed by V&R (Vaimann and Research) in USA. Before case studies, main frame and feature of the tools are introduced in brief. Case studies of the actual power system of Korea are demonstrated for checking the application possibility of POM/OPM/BOR.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.3
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• pp.168-172
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• 2013

A preliminary performance test of a 30RT 2-stage screw heat pump was carried out in order to develop a high performance large-scale unutilized energy source heat pump system, which will be used for district heating and cooling. In this study, two issues of the system operating control were investigated. The first issue is the mode switching control from 1-stage to 2-stage. A stable 2-stage heating operation is guaranteed, only if the load-side water inlet temperature is over a certain value, where the 1-stage heating operation should be done first from a cold start. The second issue is oil level control. An oil shortage problem in the low stage compressor, which depends on the degree of suction superheat, was solved by a proper oil level control scheme.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.840-845
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• 2014

Vibration profiles consist of two kinds of pattern, random and harmonic, at general engineering problems and the detailed vibration test mode of a target system is decided by the spectral condition that is exposed under operation. In moving mobility, random responses come generally from road source; whereas the harmonic responses are triggered from rotating machinery parts, such as combustion engine or drive shaft. Different spectral input may accumulate different damage in frequency domain since the accumulated fatigue damage dependent on the pattern of input spectrum in high cyclic loading condition. To evaluate the sensitivity of spectral damage according to different loading conditions, a linear elastic system is introduced to conduct a uniaxial vibration testing. Measured data, acceleration and strain, is analyzed using energy isocline function and then, the calculated fatigue damage is compared by different loading cases, random and harmonic.