• Informatization Policy
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• v.17 no.3
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• pp.57-73
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• 2010

The objective of this study is to assess the economic impacts that ensue from the ubiquitous spectrum monitoring project(u-SMP) by employing a contingent valuation method(CVM) to provide policy-makers with useful and responsible information. Importance of investigating the u-SMP service and its economic desirability cannot be overemphasized to actively cope with varying environment for spectrum use in that the spectrum monitoring contributes to the public welfare. According to estimating results, annually WTP per household is 1,268 Korean Won. Consequently, the annual benefit of u-SMP is about 7.9 billion Korean won. This result contributes to robust policy-makings for the u-SMP, to uncovering the economic value of the u-SMP, and to obtaining policy implications for activating the spectrum use.

• Journal of Korea Multimedia Society
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• v.15 no.3
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• pp.372-379
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• 2012

This paper presents a group based propagation method for multi-hop transmission, in order to deliver an emergency message to the reasonable size of vehicle troop. A group head is selected in considering of the position information of vehicles and radio transmission range. With benefits of the group based transmission, it is possible to minimize the unnecessary transmissions and the possibility of message collisions. We evaluate the performance of the proposed scheme compared with conventional schemes. Simulation results show that the message propagation performance is so stable regardless of vehicle's congestion degree.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.51-56
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• 2014

TETRA(TErrestrial Trunked RAdio) provide specialized disaster radio communication services as a standard European for digital TRS(Trunked Radio System). Especially, DMO(Direct Mode Operation) feature is used effectively in the radio shadow areas which base station does not propagate radio signal because it can communicate directly with terminal to terminal without base station's relay function. However, to effectively used DMO feature, radio coverage prediction information should be provided to users. Therefore in this paper, we were calculated link budget of TETRA DMO terminals which were distributing and operating in the country and then predicted reaching distance about radio propagation to be applied with path loss model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2528-2533
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• 2010

This paper describes on a software simulator that can be used for an anti-ARM system. The proposed simulator is a valuable tool for investigating the optimum deployment of decoy antennas which are widely using for anti-ARM and calculating the electromagnetic field at the ARM receiver. To verify the effect of decoy antennas, we analyze the field intensity and phase at the receiver. We conduct an analysis of ARM attack in case of using multiple decoy antennas and the proposed simulator can be used to decide the optimum positions of the decoys.

• International Area Studies Review
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• v.14 no.1
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• pp.3-29
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• 2010

The purpose of this paper is to examine the transmission of domestic and foreign real and monetary disturbances into a small country with heavy imports of intermediate goods, and to analyze how the wage indexation in a small country affects the transmission of foreign disturbances into a small country. We consider the two countries, a small country and the rest of the world, two goods, and rational expectations world model under flexible exchange rate system with perfect capital mobility. We find out that foreign disturbances are transmitted into a small country through the price channel, the foreign output multiplier channel, and the nominal interest rate channel, and the foreign real balance channel. We have conducted an empirical investigation by using the Korean data for a small country and the U.S. data for a large country to see how real and monetary disturbances originating from the US affects the Korean economy with wage indexation.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.1-8
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• 2007

Although the Java bytecode has numerous advantages. there ate also shortcomings such as slow execution speed and difficulty in analysis. Therefore. in order for the Java class file to be effectively executed under the execution environment such as the network, it is necessary to convert it into optimized code. We implements CTOC. CTOC generated CFG using the existing bytecode then created the SSA Form for analysis and optimization. However. due to insertion or the ${\phi}$-function in the process of conversion into the SSA Form, the number of nodes increased. As a means of reducing the number of nodes, we performed copy propagation, which is an optimization method applicable to the SSA form. Copy propagation is the process of a value of a variable being topied to another variable. There are cases where conversion due to copy propagation alone does not yield significant effects. However, when variables are not used in the later optimization stages, copy propagation provides a means for eliminating the copy statement for the corresponding variable, making it an important step. This paper shows the copy propagation to obtain a more optimized code in SSA Form.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.1-12
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• 1997

The acousto-optical spectrometer as a new type backend of the receiver system for radio astronomical observations is manufactured for radio signal analysis. We studied on the effect of Acousto-Optic and Acousto-Optic devices and designed the optics system. We manufactured the optical mount and the CCD detector for deflected beam and interface card. This acousto-optical spectrometer consisted of a laser, optics, acousto-optic deflector, CCD detector and Interface card. This system use He-Ne laser as a light source and use optics to get parallel beam and to focus the deflected beam. Acousto-optic deflector converts IF signal to ultrasonic wave and deflect the laser beam according to the Bragg deflection. The ultra wide band acousto-optic deflector has 1 GHz bandwidth and a total of 2,048 channel Charge Coupled Device for signal detection. In this study, we discuss the theoretical description on the effect of Acousto-optics, the design of the optics, manufacture of optical mount, CCD detector, interface card and we presented the results of experiment. As a result of measurement, we have 1,000 channels bandwidth from CCD channels.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.2
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• pp.57-63
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• 2004

Wave lengths of tsunamis are shorter than those of tides, and the dispersion effect of tsunamis is relatively strong. Thus, it should be properly considered in the numerical simulation of distant tsunami propagation for better accuracy. In the present study an active dispersion-correction scheme using explicit scheme is developed to take into account the dispersion effect in the simulation of tsunami propagation using one-dimensional finite element method based on wave equation. The validity of the dispersion-correction scheme proposed in this study is confirmed through the comparision of numerical solutions calculated using the present scheme with analytical ones considering dispersion effect of waves.

• Geotechnical Engineering
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• v.14 no.4
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• pp.117-128
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• 1998

Solid mattress foundation using geogrid has often been used on soft grounds to increase the bearing capacity, and its effect has received much recognition. Geogrid-mattress system is the method of construction which increases the bearing capacity and the effect of controlling settlement by dispersing load to wider foundation through its stiffness. But ifs mechanism has not been examined exactly yet. considered to be influential factors in the experiments. As a result of the experiments, the characteristic of dispersing stress under mattress foundations was understood and the way of calculating the bearing capacity in designing the mattress foundations was suggested.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.321-330
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• 2011

We experimentally investigated the effect of applied DC electric fields on the flame spread over polyethylene-coated electrical wire. The flame-spread rates over electrical wire with negative and positive DC electric fields from 0 to ${\pm}7$ kV were measured and analyzed. We compared the results for DC electric fields with previous results for AC electric fields. We explored whether or not various flame shapes could be obtained with DC electric fields and the main reason for the flame-spread acceleration, particularly at the end of the electrical wire, for AC electric fields. We found that DC electric fields do not significantly affect the flame-spread rates. However, the flame shape is mildly altered by the ionic wind effect even for DC electric fields. The flame-spread rate is relevant to the flame shape and the slanted direction in spite of the mild impact. A possible explanation for the flame spread is given by a thermal-balance mechanism and fuel-vapor jet.