• Journal of Korean Society of Transportation
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• v.15 no.4
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• pp.53-71
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• 1997

This paper presents a methodology for estimating average travel speed using volume and occupancy data from single magnetic loop detectors for signalized arterials. Three methods were developed and evaluated using field data: VPLUSKO method, fuzzy control method, and neural network method. While the VPLUSKO method is easy to apply, it results poor performances compared to other methods. The neural network method showed the best performances among the candidate methods. This method revealed the weakness in transferability, however. From limited cases of field test, it was concluded that the method of the fuzzy control application showed reasonable performance of estimation. It was also demonstrated that the fuzzy control method has the capability of transferability.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2006.05a
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• pp.20-25
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• 2006

차량 내에서 보내는 시간이 많은 현대인들에게 도로 내 여러 가지 상황 정보를 제공해 줄 수 있는 텔레매틱스 서비스가 점점 각광을 받고 있다. 도로 내 설치되어 있는 차량 검지기와 GPS(Global Positioning System) 기술을 통해 고수준의 교통 정보가 수집되고 있지만, 이를 가공하여 도로상의 운전자들에게 전달하는 방법은 최근 들어 활발하게 연구 중에 있다. 텔레매틱스 서비스 중 가장 중요한 서비스는 운전자가 요청하는 교통 상황 정보를 신속하고 정확하게 전달해 주는 것이다. 본 연구에서는 가까운 과거의 패턴 자료를 이용하여 필터링 범위를 산정한 후, 정상적인 흐름에 반하는 이상 자료들을 실시간으로 제거하여 신뢰성 있는 링크대표속도 값을 제공하는 방법을 제시한다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.21-30
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• 2008

The travel speed collected by the prove-car equipped with the GPS has the problems, which are the data's stability and finding out the representative travel speed, by the influence of the traffic signal and etc. at the interrupted traffic. This study was conducted to develop the method of filtering the outlier data from the data collected by the prove-car. The method to remove the outlier data from the serial data which were collected by the prove-car was adapted to each of the quartile deviation statistics model and the management graphic statistics model. The rate of removing the outlier data by the quartile deviation method was $0{\sim}3.7%$ while the rate by the management graphic statistic methods was $0.3{\sim}7.2%$. Both methods show the low removal rate at the dawn time when the traffic is inactivity, on the other hand the remove rate is high during the daytime. However, both methods have the problem such that the threshold level for removing the outlier data was established at the low bound in the case as good as the statistics model. Therefore, it is required for the experience calibration.

• Journal of Korean Society of Transportation
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• v.30 no.5
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• pp.71-82
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• 2012

Some previous studies adopted a method statistically based on the observed traffic volumes and travel times to estimate the parameters. Others tried to find an optimal set of parameters to minimize the gap between the observed and estimated traffic volumes using, for instance, a combined optimization model with a traffic assignment model. The latter is frequently used in a large-scale network that has a capability to find a set of optimal parameter values, but its appropriateness has never been demonstrated. Thus, we developed a methodology to estimate a set of parameter values of BPR(Bureau of Public Road) function using Harmony Search (HS) method. HS was developed in early 2000, and is a global search method proven to be superior to other global search methods (e.g. Genetic Algorithm or Tabu search). However, it has rarely been adopted in transportation research arena yet. The HS based transportation network calibration algorithm developed in this study is tested using a grid network, and its outcomes are compared to those from incremental method (Incre) and Golden Section (GS) method. It is found that the HS algorithm outperforms Incre and GS for copying the given observed link traffic counts, and it is also pointed out that the popular optimal network calibration techniques based on an objective function of traffic volume replication are lacking the capability to find appropriate free flow travel speed and ${\alpha}$ value.

• ETRI Journal
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• v.40 no.1
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• pp.39-50
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• 2018

More people prefer using rail traffic for travel or for commuting owing to its convenience and flexibility. The railway scenario has become an important communication scenario in the fifth generation era. The communication system should be designed to support high-data-rate demands with seamless connectivity at a high mobility. In this paper, the channel characteristics are studied and modeled for the railway tunnel scenario with straight and curved route shapes. On the basis of measurements using the "Mobile Hotspot Network" system, a three-dimensional ray tracer (RT) is calibrated and validated for the target scenarios. More channel characteristics are explored via RT simulations at 25.25 GHz with a 500-MHz bandwidth. The key channel parameters are extracted, provided, and incorporated into a 3rd-Generation-Partnership-Project-like stochastic channel generator. The necessary channel information can be practically realized, which can support the link-level and system-level design of the communication system in similar scenarios.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.7-16
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• 2004

The homogeneous road section is defined as one consisted of similar traffic characteristics focused on demand and supply. The criteria, in the aspect of demand, are the diverging rate and the ratio of green time to cycle time at signalized intersection, and distance between the signalized intersections. The criteria, in that or supply, are the traffic patterns such as traffic volume and its speed. In this study, the effective method to generate valuable data, pointing out the problems of removal method of obscure data, is proposed using data collected from Gonjiam IC to Jangji IC on the national highway No.3. Travel times are collected with licence matching method and traffic volume and speed are collected from detectors. Futhermore, the method of selecting homogeneous road section is proposed considering demand and supply aspect simultaneously. This method using outlier filtering algorithm can be applied to generate the travel time forecasting model and to revise the obscured of missing data transmitting from detectors. The point and link data collected at the same time on the rational highway can be used as a basis predicting the travel time and revising the obscured data in the future.

• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.29-39
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• 1999

An earlier study of the effect of rain found that the capacity of freeway systems was reduced, but did not address the effects of rain on the nature of traffic flows. Indeed, the substantial variation due to the intensity of adverse weather conditions is entirely rational so that its effects must be considered in freeway facility design. However, all of the data in Highway Capacity Manual(HCM) have come from ideal conditions. The primary objective of this study is to investigate the effect of rain on urban freeway traffic flows in Seoul. To do so, the relations between three key traffic variables(flow rates, speed, occupancy), their threshold values between congested and uncontested traffic flow regimes, and speed distribution were investigated. The traffic data from Olympic Expressway in Seoul were obtained from Imagine Detection System (Autoscope) with 30 seconds and 1 minute time periods. The slope of the regression line relating flow to occupancy in the uncongested regime decreases when it is raining. In essence, this result indicates that the average service flow rate (it may be interpreted as a capacity of freeway) is reduced as weather conditions deteriorate. The reduction is in the range between 10 and 20%, which agrees with the range proposed by 1994 US HCM. It is noteworthy that the service flow rates of inner lanes are relatively higher than those of other lanes. The average speed is also reduced in rainy day, but the flow-speed relationship and the threshold values of speed and occupancy (these are called critical speed and critical occupancy) are not very sensitive to the weather conditions.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.3
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• pp.78-88
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• 2014

Now, UTIS collects and provides traffic information by building RSE 1,150(unit) and OBE about 51,000(vehicle). it's inevitable to enlarge traffic information sources which use to improve quality of UTIS traffic information for Stabilizing UTIS's service. but there are missing data sections. And, In this study as a way to overcome these problems, based on BIS(Bus information system) installed and operating in the capital area to develop normal vehicle's link transit time estimation model which is used realtime collecting BMS data, we'll utilize the model to provide missing data section's information. For these problem, we selected partial section of suwon-city, anyang-city followed by drive only way or not and conducted model estimating and verification each of BMS data and UTIS traffic information. Consequently, Case2,4,6,8 presented highly credibility between UTIS communication data and estimated value but In the Case 3,5 we determined to replace communication data of UTIS' missing data section too hard for large error. So we need to apply high credibility model formula adjusting road managing condition and the situation of object section.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.101-112
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• 2006

Currently, highway design speed is determined by considering highway function, area type, and terrain type. Sometime it is pointed out that determining a reasonable design speed which is both efficient and safe is not an easy task and that Practicing engineers often select an unsuitable design speed on purpose, capitalizing on some ambiguous and discretionary expressions in describing the highway design speed. This undesirable Problem is arising mostly due to the fact, that the current geometric design standard fails to include rolling terrain type and can not reflect the whole characteristics of land use patterns adjacent to the design highway route. A recent research was Published considering this problem and it attempted to improve the highway design speed determining process. In this research Project, tn see the effects of this recently developed procedure, a new and reduced design speed was calculated based on the new Procedure and subsequently another highway design route was selected. The travel time. construction cost. and the expected degree of safety associated with the new route were assessed to be compared with the ones with the existing procedure. As a result. it was found that the new procedure was successful in reflecting the localities such as terrain type and area type into better determining highway design speed, eliminating much of highway engineers' discretion when applying engineering judgments. Also the new Procedure is keen to produce a more economical highway project. In other words, despite of producing reduced amount of user benefits accrued, in the new highway route, the construction cost has been cut significantly leading to higher values in B/C. NPV, and IRR. Also EMME-II output, which Provided the link assigned volumes, rendered only a slightly reduced Levels of Service along surrounding links in the study network. This reduction was believed to occur because of lower design speed and it had been expected from the beginning.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.285-295
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• 2018

Purpose: The aim of this study is to develop a three-wheel riding cultivator for improving the performance of the current four-wheel riding cultivators in the market. Methods: A prototype three-wheel riding cultivator with the rated power of 15.5-kW, a primary hydrostatic and a two-speed selective gear transmission shifts, front/rear three-wheel drive, a hydraulic wheel tread adjustment, and the mid-section attachment of the major implements was designed and constructed. Its specifications and basic performance are investigated. Results: The maximum speeds of the prototype at the low and high stages were measured to be approximately 7.31, and 11.29 km/h in forward travel, respectively, and approximately 3.60, and 6.37 km/h in rearward travel, respectively. The minimum ground clearance is shown to be 670 mm. The rotating speeds of the power takeoff (PTO) shaft at the low and high stages are shown to be approximately 795 and 1,140 rpm, respectively. The tread of the rear wheels, the minimum radius of turning, and the maximum lifting height of the parallel link device are measured to be within 1,320-1,720 mm, 2.80 m, and 390 mm, respectively. Approximately 25.3% and 74.7% of the total weight of the prototype are distributed in the front and rear wheels on flat ground, respectively. When the tread of rear wheels increased from 1,320 to 1,720 mm, the left and right static lateral overturning angles increased from $33.4^{\circ}$ to $39.1^{\circ}$ and from $29.0^{\circ}$ to $36.1^{\circ}$, respectively. Conclusions: The prototype three-wheel riding cultivator showed a wide range of travel and PTO speeds, high minimum ground clearance, small minimum radius of turning, and easy control of the rear wheel tread. Further, the easy observation of cultivating operations by mid-mounting the implements can improve quality of work. Therefore, the prototype is expected to contribute to the riding mechanization of cultivating operations for various upland crops in Korea.