Impacts of Radio Propagation Model on Mobile Ad-hoc Network (MANET) Performance in Group Mobility Environments

Yeo, In-ho(여인호),Yang, Hyo-sik(양효식),Rhee, JongMyung(이종명) 한국정보전자통신기술학회 2010 한국정보전자통신기술학회논문지 Vol.3 No.3

As the applications for Mobile Ad-hoc NETworks (MANETs) have varied, performance analysis has become one of the main research areas. They commonly offer only simple radio propagation models that neglect obstacles of a propagation environment. The radio wave propagation model has a strong impact on the results of the simulation run. In this paper we present the new experimental results of the impacts of the various propagation models on MANETs' performance. Intensive simulations have been presented using the group mobility which models typical ad-hoc situations such as military movements or disaster recovery activities under the supervision of a group leader. Comparisons of conventional simple models with more complicated models, i.e., shadowing, Raleigh, and Ricean models, show that, in spite of the models' popularity, the free space and two-ray ground models are too optimistic in describing real ad-hoc group mobility situations.

시공간적 분석을 통한 차로간 충격량 전파모형 개발

김상구,류주현 대한교통학회 2011 대한교통학회지 Vol.29 No.3

In general, flow propagation has been explained using the shock wave theory which is expressed as a function of variations in volume and density. However, the theory has certain limitation in portraying heterogeneous flow, e.g., flow propagation between lanes. Motivated by this fact, this study seeks a new measure for analyzing the propagation characteristics of traffic flow at three sections of highway (i.e., merging area, weaving section, and basic section) from temporal and spatial perspectives, and then develops a model for estimating the measure for the flow propagation. The “shock wave speed” which is the measure widely adopted in literature, was first applied to describe the propagation characteristics, but it was hard to find distinct characteristics in the propagation. This finding inspires to develop a new measure named “Impulse Volume”. It is shown that the measure better explains the propagation characteristics at the three study sections of highway. In addition, several models are also developed by performing multi-regression analyses to explain the flow propagation between lanes. The models proposed in this paper can be distinguished in three sections and the lane placement. 지금까지 교통류의 전파현상은 밀도와 교통량의 변화에 따른 충격파 이론을 사용하여 설명되어져 왔으나 서로 다른 차로간 교통류 전파와 같은 이질적인 교통류를 해석하기위해 적용하기에는 한계가 있다. 따라서, 본 연구는 고속도로의 항공사진자료를 분석함으로써 합류부 구간과 엇갈림 구간, 기본구간의 교통류 전파특성을 시공간적으로 분석하고 차로간 교통류 전파해석을 위한 충격량 전파모형을 개발하는 것을 목적으로 한다. 본 연구에서는 기존에 사용하던 충격파 속도라는 척도를 이용하여 교통류 전파특성을 분석하고자 하였으나 전파특성에 대한 분명한 특징을 찾기가 어려웠고, 이러한 이유로 충격량이라는 새로운 척도를 개발하여 개발된 척도로 교통류 상태를 해석하고 적용하여 각 분석구간의 충격량 특성을 분석할 수 있었다. 분석된 3개 구간은 충격량의 특성이 공통적으로 발생하여 교통류 전파시 의미있는 임계치를 도출하였고, 차로간의 상호관계를 설명할 수 있는 요인을 파악하고 분석구간과 차로에 따라 다중회귀분석을 수행하여 충격량을 결정하는 차로간 충격량 전파모형을 개발하였다.

소셜 미디어를 활용한 불교 포교 고찰

박경준,정헌열,김은경,곽경희 한국선학회 2011 한국선학 Vol.28 No.-

21세기는 ‘변하지 않는 것은 없다’는 진리가 가장 확연하게 드러나는 시대이다. 기술은 하루가 다르게 변화 발전하고, 이에 따라 사람들의 생활도 변화하고 있다. 그 중심에 인터넷과 모바일이 있다. IT의 발전은 시간과 공간 제약을 무력화시켰고, 일과 놀이를 융합시켰으며, 활발한 사회 커뮤니케이션을 주도하여 신인류의 등장을 촉진시켰다. 이에 기업은 물론 정부, 종교단체 등 사회 공동체의 소통 채널이 IT를 중심으로 새로운 진영을 갖추기 위해 빠르게 대처하고 있다. 그러나 유독 불교계는 사회 변화의 흐름에 무관심한 것처럼 보인다. 서구에서 명상을 중심으로 불교 인구가 증가하고 있고, 물리학, 천문학, 의학, 심리학 등 거의 전 분야에 걸쳐 불교에 대한 학계의 관심이 증폭되고 있음에도 한국 불교는 크게 영향력을 미치지 못하고 있는 실정이다. 게다가 한국 불교 인구도 오랫동안 정체 상태에 빠져 있다. 사람들의 라이프 사이클이 급격하게 변하고 있음에도 크게 달라지지 않는 포교 방법은 그 한 원인이라고 할 것이다. 본 논문은 뉴미디어를 중심으로 변화하고 있는 현실을 진단하고, 그에 걸맞는 포교 방안을 제안하여 실제 포교에 응용할 수 있도록 길을 제시하는 것을 목적으로 한다. 이에 따라, 뉴미디어 사회의 개념과 특징을 정리하고, 뉴미디어를 활용한 다양한 집단의 사례를 분석하여 현 시대의 트렌드를 어떻게 포교에 접목할 수 있는지 상관관계를 살펴볼 것이다. 이를 바탕으로 본 논문의 주제인 뉴미디어를 활용한 포교 방안에는 어떤 것들이 있으며, 어떻게 성공할 수 있는지에 대한 실행 방안을 제안하고, 성공의 전제 조건으로서 신도 조직 재편과 포교 정책이 변화할 필요성이 있다는 것도 지적할 것이다. 이를 위해 포교 활동에 대한 기존 연구 분석과 함께 경영학에서 마케팅 전략을 수립할 때 사용하는 STP(Segmentation, Targeting, Positioning) 분석 기법과 소비자 의사결정 과정 분석을 병행하여 현 시대 흐름에 맞는 새로운 뉴미디어 포교 전략을 도출할 것이다. 이 논문을 통해 뉴미디어시대의 특성을 살려 재가 불자의 적극적인 포교 활동을 통한 불교인 유입과 한국 불교의 위상 정립이라는 포교의 선순환 구조가 확립되기를 바란다. 21st century is the era of 'Everything is changing.' Technology is getting advance every day, and people's lives are changing. Internet and mobile are in the middle of momentous change. The improvement of IT have stunned time and space, have integrated work and recreation, and have catalyzed the appearance of neoanthropinae by facilitating vigorous social communication. So Social communities include company, government, and religious group are try to cope with the change rapidly by moving their communication channel. However Buddhism looks like the only community that have no regard for the change. In West Buddhism population has been growing around meditation. In addition, Academia's attention about Buddhism is increasing throughout the whole field like physics, astronomy, medical science, psychology and so on. But Buddhism population has been decreasing especially in Korea for the long time. we can find that reason in propagation manner. Although peoples' live styles are changing so fast, the way of propagation is still old one like 1600years before. This thesis is aimed at diagnosis the changing present age around new media, suggestion the realistic propagation way, and application with that realistic propagation way. So it is going to clear up the new media society's concept and characteristics, is going to analyze various groups cases. Finally it is going to not only look into interrelation between trend and propagation, also check how to ingraft on the propagation. Based on this, this thesis will find propagation method that using new-media, will suggest successful planning strategies, and will point out the need of the propagation policy. Using STP analysis (Segmentation, Targeting, Positioning), consumer decision-making progress of marketing strategy in management field and existing research about propagation, it will draw timely new-media propagation strategy. We hope that the virtuous circle structure is established through the aggressive new-media propagation.

Modeling and simulation of hollow fiber CO_2 separation modules

정현주,여영구,한상훈,이영무 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.7

We developed two models for the CO_2 separation process by hollow-fiber membrane modules. The explicit model, which is based on mass balances for the separation modules, is compared with the multilayer perceptrons (MLP)back-propagation neural networks model. Experimental data obtained from single-stage module with recycle are used to validate the explicit model as well as to train the MLP neural model. The effectiveness of the model is demonstrated by little discrepancy between experimental data and computational results. The explicit model for the single-stage module can easily be extended to the multi(three)-stage module. Because of the lack of experimental data for multi-stage modules,computational data from the explicit model with and without recycle are used as training data set for the MLP neural model. We examined the effects of recycle on the recovery based on the results of numerical simulations, and could see that the predicting performance is improved by recycle for multi-stage module. From the results of numerical simulations,the proposed models can be effectively used in the analysis and operation of gas separation processes by hollowfiber membrane modules.

슬래머 웜 전파과정 분석을 위한 네트워크 모델링 및 시뮬레이터 구현

임재명,윤종호,Lim, Jae-Myung,Yoon, Chong-Ho 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.5B

본 논문에서는 2003년 국내 뿐만 아니라 전세계의 인터넷망에서의 심각한 소통장애를 일으켰던 슬래머 웜 보안공격의 전파과정에 대한 새로운 통신망 모델을 제시하고 NS-2를 이용한 시뮬레이터를 구현하여 웜 보안공격에 의한 전파과정을 분석하였다. 기존 DN-AN모델을 Abstract network-Abstract network(AN-AN)모델로 추상화함으로써 국내 뿐만 아니라 전 세계의 수많은 호스트를 대상으로 한 대규모 인터넷망에 대하여 최초의 웜 패킷이 국내의 인터넷 국제관문국으로 유입된 시점부터 국내의 망이 포화되는 전 과정을 시간대별로 분석할 수 있는 NS-2용 시뮬레이터를 구현하였다. 또한 구현된 시뮬레이터는 감염된 국내의 호스트에 의해 국외의 호스트를 감염시키는 과정도 분석 가능하였다. 시뮬레이션 결과 290초만에 8,848개의 국내 호스트가 감염되었고, 308초만에 66,152개의 국외 호스트가 감염되었다. 또한 공격시 수행되는 웜 감염 전파과정에 의해 국내로 유입되거나 국외로 유출되는 웜 감염패킷들은 국제관문국에서 각각 154초와 135초내에 포화됨을 알 수 있었다. In this paper, we present a simulation model of Slammer worm propagation process which caused serious disruptions on Internet in the you of 2003 and analyze the process of Slammer by using NS-2. Recently introduced NS-2 modeling called "Detailed Network-Abstract Network Model" had enabled packet level analysis. However, it had deficiency of accommodating only small sized network. By extending the NS-2 DN-AN model to AN-AN model (Abstract Network-Abstract Network model), it is effectively simulated that the whole process from the initial infection to the total network congestion on hourly basis not only for the Korean network but also for the rest of the world networks. Furthermore, the progress of the propagation from Korean network to the other country was also simulated through the AN-AN model. 8,848 hosts in Korean network were infected in 290 second and 66,152 overseas hosts were infected in 308 second. Moreover, the scanning traffics of the worm at the Korean international gateway saturated the total bandwidth in 154 seconds for the inbound traffic and in 135 seconds for the outbound one.

An Accurate Radio Channel Model for Wireless Sensor Networks Simulation

Alejandro Martfnez-Sala,Jose-Maria Molina-Garcia-Pardo,Esteban Egea-Lopez,Javier Vales-Alonso,Leandro Juan-Llacer,Joan Garcia-Haro The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.4

Simulations are currently an essential tool to develop and test wireless sensor networks (WSNs) protocols and to analyze future WSNs applications performance. Researchers often simulate their proposals rather than deploying high-cost test-beds or develop complex mathematical analysis. However, simulation results rely on physical layer assumptions, which are not usually accurate enough to capture the real behavior of a WSN. Such an issue can lead to mistaken or questionable results. Besides, most of the envisioned applications for WSNs consider the nodes to be at the ground level. However, there is a lack of radio propagation characterization and validation by measurements with nodes at ground level for actual sensor hardware. In this paper, we propose to use a low-computational cost, two slope, log-normal path­loss near ground outdoor channel model at 868 MHz in WSN simulations. The model is validated by extensive real hardware measurements obtained in different scenarios. In addition, accurate model parameters are provided. This model is compared with the well-known one slope path-loss model. We demonstrate that the two slope log-normal model provides more accurate WSN simulations at almost the same computational cost as the single slope one. It is also shown that the radio propagation characterization heavily depends on the adjusted model parameters for a target deployment scenario: The model parameters have a considerable impact on the average number of neighbors and on the network connectivity.

Bluetooth Worms Propagation in Smartphone Networks with Awareness

Yongwang Gong,Haiyu He 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.9

In order to study impacts of awareness on the propagation of a Bluetooth worm in smartphone networks, a novel propagation model is proposed. In this model, the smartphone network is regarded as a two-layer network composed of a social network layer in which the awareness diffuses and a physical network layer in which the Bluetooth worm propagates. It is shown by theoretical analysis and simulations that: (1) awareness cannot change the propagation threshold, but can mitigate Bluetooth worm in terms of decreasing the propagation speed and the final infection size; (2) the structure of the social network layer has a profound impact on such mitigation effects. That is, for smaller effective infection rate  , BA structure is always more effective than WS structure; while for larger  , there exists a critical value of social reinforcement of awareness c b , beyond which BA structure is more effective than WS structure, or else the reverse is true. In addition, the critical value c b is larger with  increasing.

지역간 투입-산출 모형 기반의 평균전파길이 추정 모형

조철주 한국지역경제학회 2017 韓國地域經濟硏究 Vol.15 No.3

When industrial linkages are studied from the perspective of production chains, the average propagation length (APL) is relevant. The mathematical formula that is currently used to estimate the APL is constructed in the context of the single-region input-output model. Yet, APL estimates based on the single-region model are exposed to the problem of underestimation, which is caused from its failure to capture the segments of production chains that are formed by industrial linkages between different regions. To overcome the underestimation problem inherent to the single-region based estimation of APL, this paper proposes the formal model of measuring the APL in the context of the interregional input-output model and demonstrates the proposed model’s advantage by empirically applying it with the model to the 2015 Interregional Input-Output Table in Korea. The results of the analysis indicate that the APL should be measured by the formal model formulated in the context of the interregional input-output model, which is developed through this paper. 생산사슬의 관점에서 산업간 연계를 분석할 경우 그 측정수단으로 평균전파길이가 이용된다. 현재 평균전파길이를 추정하는데 단일지역 투입-산출 모형의 맥락에서 유도된 수리적 방법이 이용된다. 그런데 단일지역 투입-산출 모형 기반의 평균전파길이 추정치는 지역간 산업연계에 의한 생산사슬 부분을 반영하지 못하는 과소추정의 문제를 갖는다. 이러한 과소추정의 문제에 착안하여 본 연구는 지역간 투입-산출 모형의 맥락에서 평균전파길이를 추정하기 위한 수리모형을 수립하고 이를 실증적으로 적용하는데 초점을 맞춘다. 수립된 모형을 평가하기 위한 방편으로 2015지역산업연관표를 이용하여 단일지역 투입-산출의 맥락과 지역간 투입-산출 맥락에서의 평균전파길이 추정치를 비교함으로써 전자의 추정치가 갖는 과소추정의 정도를 시도별 산업별로 측정하였다. 본 연구결과는 산업생산사슬을 분석할 경우 과소추정으로 인한 왜곡을 피하기 위해서는 본 연구를 통하여 개발된 지역간 투입-산출 모형 기반의 평균전파길이 추정모형을 이용하는 것이 타당하다는 것을 보여준다.

How Far does Surface Heave Propagate? A Discussion on Analytical and Numerical Modeling of the Surface Heave Induced by Subsurface Fluid Injection

Asanga S. Nanayakkara,Ron C. K. Wong 대한토목학회 2009 KSCE Journal of Civil Engineering Vol.13 No.4

Reservoir dilations occur due to variety of subsurface injection operations including waste disposal, waterflooding, steam injection, CO₂sequestration and aquifer storage recovery. These reservoir dilations propagate to the surrounding formations and extend up to the ground surface resulting in surface heaves. This paper discusses modeling of the surface heave by applying both analytical and numerical methods. Results of the study demonstrate that the lateral extent of a finite element model has a direct impact on the surface heave profile and if the lateral boundaries are too close to the line of symmetry, there will be significant errors in the finite element results. This paper proposes a rapid way of estimating a sufficient lateral extent for the finite element model by using a new chart. The chart contains a family of curves, which can be used to estimate the surface heave propagation distance under various injection depths, injection periods and soil properties. Reservoir dilations occur due to variety of subsurface injection operations including waste disposal, waterflooding, steam injection, CO₂sequestration and aquifer storage recovery. These reservoir dilations propagate to the surrounding formations and extend up to the ground surface resulting in surface heaves. This paper discusses modeling of the surface heave by applying both analytical and numerical methods. Results of the study demonstrate that the lateral extent of a finite element model has a direct impact on the surface heave profile and if the lateral boundaries are too close to the line of symmetry, there will be significant errors in the finite element results. This paper proposes a rapid way of estimating a sufficient lateral extent for the finite element model by using a new chart. The chart contains a family of curves, which can be used to estimate the surface heave propagation distance under various injection depths, injection periods and soil properties.

LTE Signal Propagation Model-based Fingerprint DB Generation for Positioning in Emergency Rescue Situation

Cho, Seong Yun The Institute of Positioning 2020 Journal of Positioning, Navigation, and Timing Vol.9 No.3

Fingerprinting method is useful when estimating the location of a requestor based on LTE signals in an urban area. To do this, it is necessary to acquire location-based signals everywhere in the service area for fingerprint DB generation in advance. However, there may be signal uncollected area within a wide service area, which may cause a problem that the positioning accuracy of the requestor is low. In order to solve this problem, in this paper, signal propagation modeling is performed based on the obtained measurements, and based on this model, the signal information in the non-acquisition region is estimated. To this end, techniques for modeling signal propagation according to a method using measurements are proposed. The performance of the proposed techniques is verified based on the measurements obtained on a test bed selected as Seocho-gu, Seoul. As a result, it can be seen that signal propagation modeling performed based on multidivision segmented measurements has the most performance improvement.