• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.117-124
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• 2009

In this paper, we have developed communication modules for ubiquitous transportation sensor network (u-TSN). The developed module can be used for intelligent transportation services. The developed systems are based on IEEE 802.11a and IEEE 802.11g technologies for vehicle and infrastructure systems, respectively. We have found that the throughput for the developed systems is at maximum around 15 Mbps. It is reduced to 10 Mbps at a long distance and high speed condition. The performance is enough to support traffic control services in dense traffic condition.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.428-432
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• 2011

차량 통신 네트워크(VANET, Vehicle Ad hoc NETwork)는 ITS(Intelligent Transport System)의 발전과 함께 운전자의 안전 및 교통 정보, 긴급 메시지 등과 같은 서비스를 실시간으로 가능하게 할 수 있는 차세대 네트워크 기술이다. 이러한 차량 통신 네트워크는 현재 IEEE P1609에서 정의하고 있으며, WAVE(Wireless Access Vehicular Environment)로 알려져 있다. WAVE는 차량에 설치된 OBU(Onboard Unit)와 주변시설에 설치된 RSU(Road Side Unit)을 통하여 통신하며, 차량 간 통신을 지원하는 V2V(Vehicle to Vehicle)와 차량과 주변시설과의 통신을 지원하는 V2I(Vehicle to Infrastructure)로 나뉘어져 있다. 하지만 WAVE에서 정의하고 있는 네트워크 서비스(IEEE P1609.4)는 OBU와 RSU 간의 네트워크 서비스에 초점을 맞추고 있기 때문에 전체 네트워크의 QoS를 보장하기에는 미흡한 상태이다. 따라서 본 논문에서는 차량 통신 네트워크에서 End-to-End 간의 QoS 보장을 위한 무선 메쉬 네트워크 기반의 라우팅 알고리즘을 제안한다. 제안하는 알고리즘은 무선 메쉬 네트워크 노드의 호스트 라우터 기능을 통하여 차량 노드와 이기종 간의 네트워크 서비스를 가능하게 하며, 무선 메쉬 네트워크의 다중 채널을 이용하여 데이터의 중요도에 따른 차등 서비스를 지원한다. ns-2를 이용한 시뮬레이션 결과 제안하는 알고리즘이 QoS를 보장함으로써 차량 통신 네트워크의 성능을 향상시킬 수 있음을 입증하였다.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.379-385
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• 2013

MANET is not suitable to be applied to vehicle environments because of frequent path loss and path re-routing. To solve these problem, It is known that location-based routing protocol VANET is efficient. But, the VANET algorithm does not consider urban environments due to frequent vehicle movement and jamming by tall building. In this paper, we propose an efficient routing protocol to improve transfer efficiency and reduce transfer hop count. in urban networks.

• The Journal of the Convergence on Culture Technology
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• v.4 no.1
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• pp.285-290
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• 2018

Vehicular ad hoc network (VANET) is one of the future communication technologies in which it offers safe-driving information and Internet access for both drivers and passengers by communicating among cars on the road. In case of applying Content Centric Network (CCN) rather than TCP/IP over VANET, called VCCN, it can provide efficient multicast communication of shared information among participating cars as well as offer corresponding one-to-one communications. This paper introduces SUMO for simulating traffic flows, VANET for car-to-car ad hoc communications, and CCN for a future Internet architecture. In addition, it compares and analyses the transmission performance of moving cars over VCCN. According to the simulation results using SUMO and VCCN, the larger the packet size, the better the transmission performance. In addition, VCCN provides higher packet transmission rate than that of TCP/IP when the clients shares the same contents. Furthermore, the overall data reception rate exceeds the physical transmission channel rate.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.2
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• pp.186-190
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• 2015

Intelligent vehicle plans motion and navigate itself based on the surrounding environment perception. Hence, the precise environment recognition is an essential part of self-driving vehicle. There exist many vulnerable road users (e.g. vehicle, pedestrians) on vehicular driving environment, the vehicle must percept all the dynamic obstacles accurately for safety. In this paper, we propose an multiple vehicle tracking algorithm using microwave radar. Our proposed system includes various special features. First, exceptional radar measurement model for vehicle, concentrated on the corner, is described by mixture density network (MDN), and applied to particle filter weighting. Also, to conquer the curse of dimensionality of particle filter and estimate the time-varying number of multi-target states, reversible jump markov chain monte carlo (RJMCMC) is used to sampling step of the proposed algorithm. The robustness of the proposed algorithm is demonstrated through several computer simulations.

• Journal of Preventive Medicine and Public Health
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• v.55 no.1
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• pp.49-59
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• 2022

Objectives: Access to maternal and neonatal care services (MNCS) is an important goal of health policy in developing countries. In this study, we proposed a 3-level hierarchical location-allocation model to maximize the coverage of MNCS providers in Iran. Methods: First, the necessary criteria for designing an MNCS network were explored. Birth data, including gestational age and birth weight, were collected from the data bank of the Iranian Maternal and Neonatal Network national registry based on 3 service levels (I, II, and III). Vehicular travel times between the points of demand and MNCS providers were considered. Alternative MNCS were mapped in some cities to reduce access difficulties. Results: It was found that 130, 121, and 86 MNCS providers were needed to respond to level I, II, and III demands, respectively, in 373 cities. Service level III was not available in 39 cities within the determined travel time, which led to an increased average travel time of 173 minutes to the nearest MNCS provider. Conclusions: This study revealed inequalities in the distribution of MNCS providers. Management of the distribution of MNCS providers can be used to enhance spatial access to health services and reduce the risk of neonatal mortality and morbidity. This method may provide a sustainable healthcare solution at the policy and decision-making level for regional, or even universal, healthcare networks.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.3
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• pp.48-58
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• 2009

Geo-graphical routing protocols as GPSR are known to be very suitable and useful for vehicular ad-hoc networks. However, a corresponding node can include some stale neighbor nodes being out of a transmission range, and the stale nodes are pone to get a high priority to be a next relay node in the greedy mode. In addition, some useful redundant information can be eliminated during planarization in the recovery mode. This paper deals with a new recovery mode, the Greedy Border Superiority Routing(GBSR), along with an Adaptive Neighbor list Management(ANM) scheme. Each node can easily treat stale nodes on its neighbor list by means of comparing previous and current Position of a neighbor. When a node meets the local maximum, it makes use of a border superior graph to recover from it. This approach improve the packet delivery ratio while it decreases the time to recover from the local maximum. We evaluate the performance of the proposed methods using a network simulator. The results shown that the proposed protocol reveals much better performance than GPSR protocol. Please Put the of paper here.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.4
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• pp.401-411
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• 2005

This study was conducted to develop a method to be able to estimate the vehicular emissions according to spatial scales-Seoul province, 25 counties and hundreds of grids $(1km{\times}1km)$. First, the emissions at each spatial scale was calculated by using the road network and the travel volume and speed of each link modeled by travel demand model (TDM). Second, the emission at each spatial scale was calculated on the basis of average speeds estimated by using three kinds of averaging method. These are called the provincial, volume-delay function (VDF) and zonal method, respectively. Third, three kinds of emissions and those by TDM are compared each other at three spatial scales. In Seoul (provincial scale), three kinds of emissions are less than those by TDM, but the differences of TDM from three speed averaging methods (SAMs) are small. The relative ratios of three SAMs to TDM are $88\~90\%\;in\;CO,\;99\~100\%\;in\;NOx,\;84\~85\%$ in VOCs. At county scale, NOx among three pollutants showed the highest correlation between TDM and three SAMs and the zonal method among three SAMs was proven to be the highest correlation with TDM. NOx showed the coefficients $(R^2)$ greater than 0.9 in all three SAMs but CO and VOC showed the coefficients $(R^2)$ greater than 0.9 in only zonal method. Slopes of co..elations of all pollutants showed the values close to '1' in zonal method. In the other two SAMs, slopes of NOx showed the values close to '1', but those of CO and VOC showed the values less than 0.85. At grid scale, correlations between TDM and three SAMs were not high. CO showed $0.68\~0.77\;in\;R^2s\;and\;58\~0.68$ in slopes. NOx showed $0.90\~0.94\;in\;R^2s\;and\;0.86\~0.94$ in slopes. VOC showed $0.56\~0.70\;in\;R^2s\;and\;0.48\~0.57$ in slopes. There are not high correlations between TDM and three SAMs in grid scale. This study showed that there is the most suitable method for calculating the average travel speed at each spatial scale and it is thought that the zonal method is more suitable than the VDF or provincial method.

• Journal of the Korea Society of Computer and Information
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• v.14 no.11
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• pp.105-111
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• 2009

The study aims to propose the intelligent clustering technique that calculates the distance by improving the problems of multi-hop clustering technique for inter-vehicular secure communications. After calculating the distance between vehicles with no connection for rapid transit and clustering it, the connection between nodes is created through a set distance vale. Header is selected by the distance value between nodes that become the identical members, and the information within a group is transmitted to the member nodes. After selecting the header, when the header is separated due to its mobility, the urgent situation may occur. At this time, the information transfer is prepared to select the new cluster header and transmit it through using the intelligent cluster provided from node by the execution of programs included in packet. The study proposes the cluster technique of the intelligent distance estimation for the mobile Ad-hoc network that calculates the cluster with the Store-Compute-Forward method that adds computing ability to the existing Store-and-Forward routing scheme. The cluster technique of intelligent distance estimation for the mobile Ad-hoc network suggested in the study is the active and intelligent multi-hop cluster routing protocol to make secure communications.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.799-808
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• 2008

The analysis of vehicular loads reflecting the domestic traffic circumstances is necessary for the development of adequate design live load models in the analysis and design of cable-supported bridges or the development of fatigue load models to predict the remaining lifespan of the bridges. This study intends to develop an ANN(artificial neural network)-based Bridge WIM system and Influence line-based Bridge WIM system for obtaining information concerning the loads conditions of vehicles crossing bridge structures by exploiting the signals measured by strain gauges installed at the bottom surface of the bridge superstructure. This study relies on experimental data corresponding to the travelling of hundreds of random vehicles rather than on theoretical data generated through numerical simulations to secure data sets for the training and test of the ANN. In addition, data acquired from 3 types of vehicles weighed statically at measurement station and then crossing the bridge repeatedly are also exploited to examine the accuracy of the trained ANN. The results obtained through the proposed ANN-based analysis method, the influence line analysis method considering the local behavior of the bridge are compared for an example cable-stayed bridge. In view of the results related to the cable-stayed bridge, the cross beam ANN analysis method appears to provide more remarkable load analysis results than the cross beam influence line method.