• 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.

• KIEAE Journal
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• v.8 no.3
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• pp.13-18
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• 2008

Recently it is urgent issue in every department that problem from environmental disruption such as global warming. As the case of streetscape works essentially at city scenery, it is inevitable that changing from present view, which centers facilities and buildings, to environmental harmonic scenery. This study plans climate adjusting ability and improvement of thermal efficiency by putting ecological elements to buildings on a street which are essential factors of streetscape. Ultimately, this not only makes a pleasant environment but also revives being withered earth. Street-environment on eco-scape will take a part in designing sustainable city. This study acquires the way how buildings on a street get applied ecological elements as following. Roof level part : the greening surface of the rooftop(included plant box type), the greening roof as a type of pergola, the greening surface of the middle floor rooftop(included plant box type). Elevation part : climbing type, downfall type, espalier, flower bed in balcony type, wall-installing type, water wall type, other design types. Ground level part : paving the whole surface with permeability, paving the gap with permeability, plant box type, ground plant type, waterside zone, wetland, fence greening type, terrace greening type, retaining wall greening type.

• KIEAE Journal
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• v.8 no.3
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• pp.27-36
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• 2008

Urban architecture density is getting higher, and this trend is expected to continue in the future. Therefore, skyscrapers are being brought into relief as future alternative architecture beyond symbolic meaning in the aspect of demand and supply of urban space. However, skyscrapers which were newly built have many problems such as consumption of enormous amounts of energy, destruction of natural environment, and traffic jam. For this reason, environment-friendly skyscrapers based on the concept such as Green Building and Green Skyscraper started to be built around the world. However, plans or evaluation standards, which take account of the environment-friendly aspect of skyscrapers, leave much to be desired. And especially it is hard to find environment-friendly skyscrapers. Therefore, this study aims to establish the concept of environment-friendly skyscrapers that has not properly been defined, and to find realistic planning methods and practical alternatives through the analysis of the works that have brilliant ideas about environment-friendly architectural method. From the perspective of architectural planning, we did case analysis focused on site planning, form planning, elevation and floor planning, and tried to give useful ideas for high-rise architectural planning in Korea by finding practical solution focused on the active use of natural energy, saving resources, the reduction of wastes, natural architectural environment design and natural friendly system from the view of environment-friendly technological analysis.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.109-114
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• 2005

Twofish cryptographic algorithm is concise algorithm itself than Rijndael cryptographic algorithm as AES, and easy of implementation is good, but the processing speed has slow shortcoming. Therefore this paper designed improved MDS block to improve Twofish cryptographic algorithm's speed. Problem of speed decline by a bottle-neck Phenomenon of the Processing speed existed as block that existing MDS block occupies Twofish cryptosystem's critical path. To reduce multiplication that is used by operator in MDS block this Paper removed a bottle-neck phenomenon and low-speed about MDS itself using LUT operation and modulo-2 operation. Twofish cryptosystem including modified MDS block designed by these result confirmed that bring elevation of the processing speed about 10$\%$ than existing Twofish cryptosystem.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.419-424
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• 2009

This paper show about the possibility of practical application after building VR(virtual reality) data based on Airborne LiDAR data which determines complicated topography quickly for the 3D-GIS construction. In this paper, we collected Airborne LiDAR data, digital map, serial photo and a basic design. The results are expected some effective determination by 3D-GIS construction based on LiDAR data. Hereafter, because the research will be able to be given quickly topography information on ubiquitous environment the field of construction and GIS will be able to be helped.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5B
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• pp.270-276
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• 2007

The proposed LDS(Link-status Dependent Scheduling) algorithm in HR-WPAN(High Rate-Wireless Personal Area Network) up to now aims at doing only throughput elevation of the whole network, when the crucial device is connected with worst-link relatively, throughput of this device becomes aggravation. The proposed the WGS(Worst-case Guaranteed Scheduling) algorithm in this paper guarantees throughput of the device which is connected with worst-link in a certain degree as maintaining throughput of all devices identically even if a link-status changes, decreases delay of the whole network more than current LDS algorithm. Therefore proposed WGS algorithm in this paper will be useful in case of guaranteeing throughput of a device which is connected worst-link in a certain degree in a design of HR-WPAN hereafter.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.2
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• pp.71-81
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• 2014

Time synchronization system using dual frequency bands is designed and the error sources are analyzed for alternative synchronized-pseudolite navigation system (S-PNS) which aims at military application. To resolve near/far problem, dual frequency band operation is proposed instead of pulsing transmission which degrades level of reception. In dual frequency operation H/W delay should be considered to eliminate errors caused by inter-frequency bias (IFB) difference between the receivers of the pseudolites and users. When time synchronization is performed across the sea, multipath error is occurred severely since the elevation angle between pseudolites is low so total reflection can be happened. To investigate the difference of multipath effects according to location, pseudolites are set up coastal area and land area and performances are compared. The error source related with tropospheric delay is becoming dominant source as the coverage of the PNS is broadening. The tropospheric delay is measured by master pseudolite receiver directly using own pseudorange and slave pseudorange. Flight test is performed near coastal area using S-PNS equipped with developed time synchronization system and test results are also presented.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.51-59
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• 1994

The gas jet pumps serve to preduce a vacuum or can be used as gas jet compressors. These are operated on the same principle as a steam jet vacuum pump : in the driving nozzle the pressure energy of the motive medium is converted into the kinetic energy. In the diffuser the driving jet mixes with the suction medium and the kinetic energy is reconverted into the pressure enegy. The application fields of gas jet ejectors are the evacuation of siphoning installations, the elevation of liquids, the production of vacuum filters, the vacuum supporting airlift system, the evacuation of the suction line of centrifugal pumps and the ventilation of the dangerous gases to the atmosphere. The performance of gas jet ejector is influenced strongly to velocity coefficient of motive nozzle, the distance between the motive outlet to the diffuser inlet and the dimensions of diffuser. This study is performed for the computer aided design of gas jet ejectors in future. Through the present experiments, it is known that the velocity coefficient of the motive air nozzle ranges from 0.91 to 0.95 and the maximum efficiency of gas jet ejector is 24.6%.

• Structural Engineering and Mechanics
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• v.9 no.1
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• pp.17-35
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• 2000

Dynamic response of a three span continuous bridge has been determined by full scale experiments on the bridge. In the experiments, a heavy vehicle was driven across the bridge at different speeds and along different lanes of travel and the strains were recorded at different locations. The bridge was made of reinforced concrete and was asymmetric in plan and in elevation. Frequencies and modes of vibration excited by the vehicle were determined. The dependence of the dynamic amplification on bridge location and vehicle speed was investigated and dynamic amplifications up to 1.5 were recorded, which was higher than values predicted by bridge design codes. It was evident that when this asymmetric bridge was loaded by an asymmetric forcing function, higher modes, which are lateral and/or torsional in nature, were excited. Dynamic modulus of elasticity and the support stiffness influenced the natural frequencies of the bridge, which in turn influenced the dynamic amplifications. Larger than anticipated dynamic amplification factors and the excitation of lateral and/or torsional modes should be of interest and concern to bridge engineers.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.2
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• pp.275-279
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• 1993

A study using dairy heifers was conducted to determine the effect of environmental temperature on heat production differing in feed intake level. The design consisted of three levels of feed intake (low, medium and high) and two environmental chamber temperature (15 and $30^{\circ}C$) with four replications in each treatment. Rectal temperature (RT), respiration rate (RR), heart rate (HR) and heat production (HP) were then measured. At the both environmental temperature, RT, RR and HR increased with the increase in feed intake level. The RT and RR also increased with the elevation of environmental temperature. The HP of $30^{\circ}C$ was significantly higher (4.8-8.9%) than $15^{\circ}C$. The estimated metabolizable energy requirement for maintenance (MEm) was higher (p<0.05) at $30^{\circ}C$ ($554.7kJ/kg^{0.75}$ d) than $15^{\circ}C$ (464.9 kJ/kgd). It was suggested that the decreasing in productive efficiency under hot environmental conditions partly associated with the increase in HP, which associated with the change in heat loss mechanism from sensible path to evaporative path.