The recent development of information and communication technologies brings new changes to automobile traffic systems. The most typical example is the advancement of dedicated short range communication(DSRC). DSRC mainly consists of an intelligent transportation system(ITS), an electronic toll collection system(ETCS) and an advanced traveler information system(ATIS). These wireless communications often cause unnecessary electromagnetic waves, and these electromagnetic waves, in turn, cause frequent system malfunction. To solve this problem, an absorber of electromagnetic waves is suggested. In this research, various materials, such as powdered metal and iron oxides, are used to test the possibility for an effective absorption of the unnecessary electromagnetic waves. The various metal powders are made into a thin sheet form by compositing through processing. The electromagnetic characteristics(complex permittivity, complex permeability) of the fabricated sheet are measured. As a result, we achieve –6.5 dB at 940 MHz(77.6 % absorption rate) with a 1.0 mm-thickness electromagnet wave absorber, and –9.5 dB at 940 MHz(88.8 % absorption rate) with a 2.0 mm-thickness absorber.

Rest area is a space providing opportunities to use a restroom, refuel, reduce fatigue and receive mechanical maintenance services. In Korea, entering rate to rest area from mainline traffic and duration time in rest area are the key variables in the determination of size of rest area. However, there are many controversies because of inconsistency of those variables between rest areas. Moreover, cases that parking space of newly opened rest area are heavily congested which led to an early expansion are also reported frequently. Review on studies related to design variables for the size of rest area shows that they mostly focus on entering rate, the most superficial aspect of driver’s behavior with regression analysis with mainline traffic volume of and geographical condition. Also, studies did not succeed to explain the difference in entering rates of two different rest areas with similar mainline traffic volume. In this research, aggregate methodology has been adopted to overcome prior studies’ limitation. DSRC (Dedicated Short Rage Communication) data collected from RSE (Road Side Equipment) along expressway has been analyzed to construct trip trajectory of each vehicle. From the analysis of each vehicle’s trip trajectory, rest area usage pattern has been found out to be a result of each vehicle’s travel characteristics including departure time, time of the day when passing rest area, and driving duration. And as a result, data-driven analysis methodology was able to be laid out.

최근, 근거리 무선통신(DSRC), GPS 등 위치기반 및 전송기술에 힘입어 하이패스, 교통카드, 차량 내비게이션 등 다양한 데이터의 확보가 가능한 환경이 되었다. 이로 인하여 통행자의 이동과정과 교통운영 과정에서 다양한 데이터가 끊임없이 생성되고 축적되고 있으며, 향후 자율주행차량의 등장으로 그 양은 폭발적으로 증가될 것으로 판단된다. 고속도로의 경우 본선에 설치되어 있는 DSRC(Dedicated Short Range Communication) 시스템을 통하여 도로변 기지국(RSE)과 주행 차량 내 OBU와 무선통신으로 교통정보를 수집하고 있다. DSRC 시스템에서는 개별차량의 통행 궤적, 링크 통행속도 등이 수집되며, 고속도로에 설치된 총 978개소의 도로변 기지국(RSE)에서 전체 고속도로 이용차량의 약 30% 차량에 대해서 정보를 수집하고 있다 본 연구에서는 고속도로에서 수집되는 개별차량의 경로정보를 수집 및 가공하여 분석을 수행하였다. 분석의 시간적 범위는 대표 평일과 명절을 대상으로 하였으며, 세부적인 분석항목은 차종별, 시간대별로 선택하는 통행경로 및 국도우회 행태, 특정도로 구간을 통과하는 차량의 기종점, 통행거리 및 통행발생 특성 등이다.분석을 통해 고속도로 이용차량의 교통상황에 따른 통행경로 및 통행거리, 통행시간에 대한 특성이 평일과 명절에 어떻게 달라지는지, 경로별 통행시간에 따른 통행경로 이용률의 변화 등을 파악할 수 있었다. 또한 이러한 분석을 통해 산출된 결과를 고속도로 교통관리 정책에 활용할 수 있는 세부 방안을 도출하였다.

PURPOSES: This investigational survey is to observe a proper spatial aggregation method for path travel time estimation using the hi-pass DSRC system. METHODS: The links which connect the nodes of section detectors location are used for path travel time estimation traditionally. It makes some problem such as increasing accumulation errors and processing times. In this background, the new links composition methods for spatial aggregation are considered by using some types of nodes as IC, JC, RSE combination. Path travel times estimated by new aggregation methods are compared with PBM travel times by MAE, MAPE and statistical hypothesis tests. RESULTS : The results of minimum sample size and missing rate for 5 minutes aggregation interval are satisfied except for JC link path travel time in Seoul TG~Kuemho JC. Thus, it was additionally observed for minimum sample size satisfaction. In 15, 30 minutes and 1 hour aggregation intervals, all conditions are satisfied by the minimum sample size criteria. For accuracy test and statistical hypothesis test, it has been proved that RSE, Conzone, IC, JC links have equivalent errors and statistical characteristics. CONCLUSIONS : There are some errors between the PBM and the LBM methods that come from dropping vehicles by rest areas. Consequently, this survey result means each of links compositions are available for the estimation of path travel time when PBM vehicles are missed.

무선 다중경로 채널에서 데이터를 고속으로 전송할 경우, 신호는 페이딩, 심볼간 간섭 등의 영향으로 높은 에러율을 갖게 된다. 그러므로 현재 개발된 DSRC(dedicated short-range communication) 시스템의 변복조 방식은 1 Mbps이상의 데이터 서비스가 어려울 것으로 예상되므로 새로운 채널등화 기법 및 개선된 변복조 방식이 요구된다. OFDM(orthogonal frequency division multiplexing) 방식은 보호간격의 삽입을 통하여 ISI를 방지할 수 있으므로 고속 데이터 전송에 적합하다. 그러나 보호기간이 OFDM 방식에서의 각각의 심볼주기에 사용되는 채널지연 확산보다 길어지므로 채널활용의 효율성에서 상당한 손실이 야기된다. 그러므로 등화기를 고속의 데이터 전송율과 긴 채널 지연확산 조건을 가지는 ITS(intelligent transport system)에 적용하기 위해서는 ISI(inter symbol interference)를 제거할 필요가 있다. 본 논문에서는 OFDM-DSRC 시스템을 위한 채널 등화기를 설계하였으며, 다중경로 페이딩 환경에서 컴퓨터 시뮬레이션을 통해 그 성능을 분석하였다.

In this paper, we proposed the model of wireless communication for ACTS using DSRC and the DSRC system for T/C. The proposed wireless communication model is how to join with DSRC and other wireless communication in port. The DSRC system for T/C is the first application to the unit of port Facilities Automation on stacking area. The DSRC system is communicated between OBE and RSE using 5.8Hz ISM band frequency. The previous works of DSRC applications are gate automation. In these cases, the road trackers are difficult to obtain information of the port in the stacking area. So we used the DSRC for the wireless communication for the port Facilities Automation. Using DSRC, the load trackers obtain more information in the port and contacts to ITS on back-roads of port. The proposed communication system is serviced to reelection of port statistics.