• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.243-246
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• 2019

In cognitive radio networks, secondary transmitters should cease its transmission immediately under the detection of primary transmission in the spectrum they are using. Then they need to exploit another idle spectrums and resynchronize to the newly found idle spectrums. Most of related work presume the existence of separate control channel used by secondary users commonly for exchanging the information of idle spectrums. However, this presumption is not feasible in real world cognitive radio scenario. Therefore we address a proactive spectrum synchronization scheme with no need of separate control channel. Our scheme lets secondary users exchange the spectrum information periodically during normal communication process and determine the next spectrum band in advance of detecting primary transmission. We evaluate our scheme in a real world cognitive radio environments set up with USRPs.

• Journal of the korean Society of Automotive Engineers
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• v.2 no.2
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• pp.21-24
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• 1980

차량의 제동장치는 제동시 차량의 조향안정성을 유지하면서 최소한의 제동거리를 확보하는 장 치라 할 수 있다. 제동시 차량의 조향안정성 유지와 최소제동거리를 확보하기 위해서는 차량의 적절한 제동능력에 필요한 전제동토오크를 전후륜의 제동장치에 적당하게 배분시켜야 한다. 그러나 차량의 각차륜의 하중 상태는 여러 가지 적재상태와 제동시중량이동 등에 따라 변하게 되므로 고정된 제동장치로서는 전후륜의 제동토오크를 가변시킬 수 없어 설계시 빈도가 높은 조건에 맞추어 제동장치의 구성부품을 확정할 수밖에 없다. 차량에 따라서는 축하중상태의 변 화가 큰 경우와 공용화를 위하여 여러 모델의 차량에 동일제동 장치를 적용하려고 할 경우에 문제점이 따르기 마련이다. 본고에서는 제동장치의 전후륜의 제동토오크 배분에 대하여 고찰하여 설계개념을 파악하고자 한다.

• Journal of the Korean Institute of Educational Facilities
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• v.14 no.3
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• pp.27-35
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• 2007

The purpose of this research is to analyzing the welfare function of the senior citizen with similar type of compounding the school facility, to analyze the problematical point of present condition. And also propose the spatial constitution which the student and the regional senior citizen are easy to utilize on the basis of the result. In a type of educational facility composition, it became clear that a ratio and the inflection order that elderly welfare facilities occupied of vacant class room were low. In other words, in composition of a school facilities, elderly welfare facilities can be said to be an important problem. As a result of having analyzed an existing compound facilities, there was limited interchange of student and a the aged. In addition, there were problems such as learning environment by an intersection of circulation. Therefore, composition of educational facility and elderly welfare facilities is not space composition that is intersection of simple specification function. In other words, a program of the common space which is necessary for the local community formation is necessary. Setting of semi-public area proposes the function of the existing facility and actual condition of spatial use in prerequisite.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.623-631
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• 2018

In this study, the degree of deterioration of concrete was investigated in the laboratory under conditions of carbonation and freeze-thaw cycling, which are the major causes of the deterioration of its performance. In this test, the carbonated concrete was subjected to combined freeze-thaw deterioration tests for up to 300 cycles, and its dynamic elastic modulus and compressive strength were measured. The evaluation of the effect of the water-binder ratio on normal concrete subjected to combined carbonization and freezing-thawing showed that its resistibility against such combined deterioration decreased more rapidly in the concrete with a water-binder ratio of 55 % compared with that having a water-binder ratio of 35 %. In the case where the concrete was blended with a mineral admixture consisting of fly ash and blast furnace slag at the same water-binder ratio, it showed an increase of its resistibility against combined deterioration.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.91-97
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• 2013

Image and it's processing techniques are widely applied and very important in the recent IT environment. In this paper, we try to reconstruct original BMP(Bitmap) image into indexed image and codebook utilizing vector quantization and represent high quality image only with same pixel depth of previous indexed image like JPEG etc. That is, By adopting common map method onto index image with $2^n$ color codebook, image can be represented as high quality as $2^{n+1}$ color codebook. When proposed output image is compared with original BMP image, it provides as much around 2dB as higher PSNR than conventional 8 bit index image(normal JPEG). Furthermore, this improvement(2 dB higher PSNR) could be provided when using the 9 bit indexed image.

• Journal of Advanced Navigation Technology
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• v.26 no.4
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• pp.205-210
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• 2022

Drones, which have rapidly grown along with the 4th industrial revolution, spread over industries and also widely used for military purposes. In recent wars in Europe, drones are being evaluated as a game changer on the battlefield, and their importance for military use is being highlighted. The Republic of Korea Army also planned drone-bot systems including various drones suitable for echelons and missions of the military as future defense forces. The keyword of these drone-bot systems is autonomy by artificial intelligence. In addition, common use of operating platforms is required for the rapid development of various types of drones. In this paper, we propose software framework that applies diverse artificial intelligence technologies such as multi-agent system, cognitive architecture and knowledge-based context reasoning for mission autonomy and common use of military drones.

• Journal of the Economic Geographical Society of Korea
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• v.9 no.2
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• pp.243-260
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• 2006

The continuing enlargement, deepening integration of EU and penetration of extra-EU enterprise into EU market are forming a new geographical restructure of the production system. In this paper, I analyse the changing geography of the EU automotive production system. The globalization and regionalisation of production activity intensify a competition among the enterprise. The European automotive production system changes to a platform system and a modular system for a diminution of productive costs, a development of various products and a frequent innovation of products. The European automotive enterprise is restructuring geographically the production functions and products in order to promote efficiency on a new production system, enlarged production space and intensified economic integration. The European automotive industry tends to a spatial specialization and agglomeration according to the locational factors of production functions and products and the locational condition of regions. This intensifies the geographical hierarchic structure of production activity between the core and the periphery.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.29-37
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• 2010

Porous pavements can provide road users with beneficial characteristics such as skid resistance and surface water drainage under rainy condition, and they cause less tire-road noise than conventional hot mix asphalt(HMA) pavements. However, voids of porous pavements are easily clogged by road debris at early stages, which leads to frequent maintenance works. Therefore, this study focused on the way of minimizing void clogging in porous pavements. During mixture design, the quantity of coarse aggregate has been increased to form many straight void conduits (SVCs) in porous HMAs. These SVCs were found to be effective resisting the void clogging problems. Four different porous HMAs(19mm, 13mm, 10mm, and 8mm) were developed and placed on highway roads. Their performances were validated with field tests during the past four years.

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.73-82
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• 1990

Rosin-maleic anhydride adduct (RMA) was synthesized from rosin and maleic anhydride. The polyamideimides were obtained by reacting the adduct with two aromatic diisocyanates using sodium methoxide as catalyst. The yield and the inherent viscosity of polymers obtained by the reaction in NMP solvent were low because of the possible reaction of NMP solvent with diisocyanate monomer. The polymers were synthesized in solvent mixture of NMP and cosolvents such as xylene, acetophenone, benzonitrile, and nitrobenzene in order to minimize the side reaction of NMP with diisocyanates. The yield of polymer obtained by the reaction in NMP-nonpolar cosolvent mixtures was about 70% and that obtained by the reaction in NMP-polar cosolvent mixtures was over 90%, respectively. The polymers were either amorphous or poorly cystalline, and soluble only in highly polar solvents. The inherent viscosity of polymers ranges from 0.12-0.26dl/g. The results of thermal analysis showed that the polymer had good thermal stability with initial decomposition temperature over $330^{\circ}C$.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.6
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• pp.727-731
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• 2014

Nowadays, most people have been using a bicycle as a transportation or exercise. The bicycle is so indispensable to the public means of transportation. The demand of the bicycle is increasing since one is becoming advancement more and more. We propose a smart bicycle that can controls the individual parts of the bicycle by smart phone. This paper verifies and validates the problem and the advanced direction after confirming the smart phone's public bicycle to learn about market trends and the analysis of future prospects. Based on the analyzed contents of the problem and improving the direction, we implement public bicycle system with smart bicycle. The implementation of the proposed method shows the available and the effective system with the promote public health by cycling and contributing to the domestic bicycle industry.