• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.250-256
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• 2014

The wind power generation is an eco-friendly clean energy that produces almost zero $CO_2$ emission, and has a good economic feasibility. As for the location, the installation of large turbines and construction of large-scale wind farm is easier on the offshore than on the land. In Korea, it is inevitable to generate offshore wind power through the offshore wind farm, and the radio interference of larger wind power generators and offshore wind power farm to broadcasting, communication and radars is becoming a core issue for constructing the offshore wind farm. In this study, the wind power generation status and rotor blade technology trend were presented, along with the technical trend of radar radio interference reduction relating to construction of the offshore wind farm.

• Journal of the Korean Society of Systems Engineering
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• v.4 no.2
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• pp.45-54
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• 2008

This paper describes an operational concept of the network based future airborne force power using a systems engineering approach. The battlefield is changing to new system of systems that command and control by the network based BM/C4ISR. Also, it is composed of various sensors and shooters in an single theater. Future threats may be characterized as unmanned moving bodies that the strategic effect is great such as UAVs, cruise missile and tactical ballistic missiles. New threats such as low altitude stealth cruise missile may also appear. The implementation of future airborne force power network systems against these future threats is required to complex and integrated approach based on systems engineering. This work developed the operational concepts of the future airborne network system, and then derived the requirements for performing missions effectively. In addition, the scheme of future airborne force power network systems is presented.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.429-436
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• 2018

The RCS value of maritime ship is indicator of ship's stealth performance and it should be particularly measured for navy ship to ensure survivability on the battlefield. In the design phase of the navy ship, a RCS prediction should be performed to reduce RCS value and achieve ROC(Required Operational Capability) of the ship through configuration control. In operational phase, the RCS value of the ship should be measured for verifying the designed value and obtaining tactical data to take action against enemy missile. During the measurement of RCS for the ship, ship motion can be affected by roll and pitch in accordance with sea state, which should be analyzed into threat elevation from view point of enemy missile. In this paper, we propose a method to measure and analyze RCS of ship in 3-dimensions using a ship motion measuring instrument and a fixed RCS measurement system. In order to verify the proposed method, we conducted a marine experiment using a test ship in sea environment and compared the measurement data with RCS prediction value which is carried by prediction SW($CornerStone^{TM}$) using CAD model of the ship.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.451-458
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• 2014

This paper introduces a bistatic ISAR imaging technique. In bistatic geometry, the transmitter and receiver are placed in different locations. The monostatic ISAR is inadequate not only for obtaining images on targets approaching along the radar's line of sight, but also for stealth targets. In this paper, geometry, signal modeling as well as bistatic Doppler for bistatic ISAR are introduced to address these problems. Simulations results show bistatic ISAR images as well as monostatic ISAR images against target's moving scenarios, and analyze their differences for each scenario.

• Journal of IKEEE
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• v.23 no.4
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• pp.1473-1476
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• 2019

Accurate material information is very important in PCB (Printed Circuit Board) design. In an integrated mast of a battleship, heat reduction is essential for stealth functionality. So heat dissipation from internal control equipments should be reduced as much as possible. Control equipments mostly consist of PCBs, but it often suffers from impedance mismatching due to imprecise Dk (Dielectric Constant), which significantly increases heat dissipation. In this paper, measurement methods of Dk is investigated. Also, effects on impedance mismatch by Dk variation with operating frequency is investigated.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.2
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• pp.171-175
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• 2017

The high-tech large warships are minimal and they are always monitored by opponents, and become primary targets when conflicts occur. The improvement in reducing susceptibility has significant importance because it is difficult for a ship to maintain mission capability and functionality once it is damaged. Ordinary decoys are effective only under the premise that the ship has already been exposed. Traditionally, for naval vessels, techniques related to the radar have been used in military stealth techniques to ensure confidentiality. The corner reflector, on the other hand, can produce rather large radar cross sections. Continued use of deceptive systems such as chaff during operations will help to improve survivability of naval ships. From this viewpoint, corner reflector was considered for making radar countermeasures and deception technology. This paper reviews the current status of corner reflector basis decoys and the technical feasibility of corner reflectors for developing structural decoys.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.112-120
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• 2005

The solid propellants have been most widely used for the military rockets or missiles all over the world and the efforts have been focused on the enhancement of propellant performance up to 1980s. lately in company with the distinguished development in the intelligence and communication technology, the more accurate guidance as well as maneuverability has been required in the military weapon system. To meet the requirements such as a high maneuverability, insensitiveness, or stealth of missile, the researches have been doing to develop the solid propellants which have a quality of ultra-fast burning rate, insensitiveness, low signature or the like.

• Composites Research
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• v.17 no.5
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• pp.68-77
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• 2004

The electromagnetic (EM) absorption or shielding characteristics of a material is an important issue not only for military purpose but also for commercial purposes such as radar, electric or telecommunication devices. In order to design the effective electromagnetic wave absorber, the electromagnetic characteristics of the constituents of the material should be available in target frequency band. Also, it must be possible to predict the electromagnetic properties of absorbers with respect to the content of lossy ingredients. In this study, the dielectric properties of unsaturated polyester resins containing nano-size conductive carbon black powder were measured with a free space method in the X-band frequency range and analyzed with respect to the content of carbon black. Finally, the method for estimating the dielectric properties of polymeric resin containing conductive carbon black with respect to the EM frequency was developed and verified.

• Journal of Labour Economics
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• v.25 no.2
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• pp.79-107
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• 2002

Britain's public services, especially health service and secondary education are in disarray. The current British government adopted the public-private partnership(PPP) as a major device to bring about public sector reform. In principle, PPPs could be used to outsource all sorts of public services, helping to raise standards by extending choice and competition. Up to now, however, they have been focused mainly on a relatively limited range of ancillary services related to new buildings and their subsequent operation. The unions, especially the unions covering the public sector employees are antagonistic to the PPPs. The unions have been opposing privatizing or resecting of any part of the public services, as these apt to lead insecurity of employment and degradation of working conditions of their members. Most of the union leaders consider that PPPs are 'privatization by stealth'. Even in Britain, which has a long history of trade union movements, to persuade the unions to co-operate to the reform policy has been extremely difficult. To succeed in public sector reform, the government, be it Korean or British, needs strong leadership, consistency in policies between various departments, and persuasive ability to overcome the opposition from the vested-interest group.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.187-192
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• 2006

Helicopter noise has been considered as one of major design factors like a performance and safety since the public acceptance, comfortability and stealth aspects were important for customers. According to the airworthiness regulation, the noise levels in throe different flight conditions shall comply with the specific limits. Main and tail rotors noise is most dominant in far field due to the low and mid range frequency characteristics. It is an air-born noise so That the accurate aerodynamic data is necessary for the accurate noise prediction. In KARI, low noise main and tail rotors as well as analysis codes have been developed since 2000. The approach for low noise main rotor is a kind of tip modifications, so called twin vortices tip to reduce the BVI noise. Analysis results show the 9.3dB reduction in terms of pseudo EPNL. The uneven spacing concept is applied for low noise tail rotor. Three or four decibel noise reduction is achieved by new optimized uneven spacing. Rotor noise and aerodynamic prediction codes have been improved also.