• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.3
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• pp.38-51
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• 2020

A bottleneck and congestion occur when a freeway is closed due to maintenance and construction activities on the freeway. Although various traffic managements have been developed to improve the traffic efficiency at freeway work zones, such as merge control, there is a limit to those controls with human drivers. On the other hand, the wireless communication of connected and automated vehicles (CAVs) enables the operation of advanced traffic management. This study developed a traffic control strategy that integrates Dynamic Merge Control (DMC) and Lane Change Control (LCC) in a CAV environment. DMC operates as an either early or late merge based on the occupancy rate of upstream of the work zone. The LCC algorithm determines the number of vehicles that need to change their lane to balance the traffic volume on open lanes. The simulation results showed that integrated control improves the cumulative vehicle count, average speed upstream, and average network travel time.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.1
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• pp.52-65
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• 2016

The electronic toll collection system(ETCS), is globally used in about 40 countries. In Korea, the Korea Expressway Corporation led the nationwide introduction of the ETC system in 2007 under the brand name of the Hi-pass. Since then, Hi-pass, with its rate of average daily use reaching about 70%, has become an essential facility in Korean expressways. To identify users' perception on Hi-pass (satisfaction, preference, etc.), this study conducted a Modified Importance-Performance Analysis (M-IPA). With this, this study attempted to identify the kind of efforts necessary to enhance current Hi-pass users' convenience and satisfaction. According to the result of M-IPA, the items including "non-stop payment" and "toll discount" are identified as key items that require further improvement. For improvement in the "non-stop payment" item, operations of Hi-pass toll booths appropriate for the demand for Hi-pass use and the selection of Hi-pass booths' locations in consideration of entry and exit lanes need to be improved. In addition, with regard to the "toll discount" item, although toll discount is currently provided to Hi-pass users, thus, PR thereof will have to be strengthened. It is expected that this study will be used as basic data to devise methods of enhancing Hi-pass usage through improvement of Hi-pass users' satisfaction.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.65-72
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• 1988

This study was conducted to examine the effects of trampling intensity and frequency on the change of forest bed soil and vegetation by experimental trampling. 23 experimental lanes($0.3{\times}5.0m$) were established at non-trampled Quercus acutissima stand in Suweon, Gyunggi-Do, Korea. And soil compaction and ground vegetation were examined during and after 4 weeks trampling. Increasing in trampling intensity resulted in decreasing increment rate of soil compaction and after 400 passes of trampling, soil hardness showed $11.32kg{\cdot}cm^{-2}$, (23.8mm) which affected root growth badly. At the same trampling intensity, soil compaction was high where trampling was spread over a longer period of time. The difference of soil compaction by trampling frequency was not significant below 200 passes, but 16X(every other day trampling) type resulted in the highest soil compaction over 400 passes of trampling intensity. The relative coverage of vegetation was more severely decreased than the relative density by trampling, 16X type of Trampling frequency resulted in most servere vegetational change and difference among trampling frequencies showed significance in case of 200 passes, contrasting to soil compaction.

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.17-24
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• 2010

As various social problems occur due to increasing traffic accidents, the government has setup and executed strong safety policies. As a result, the number of traffic accidents and the death toll have been decreasing in recent years. However, the setup and execution of the various policies for reducing traffic accidents cost much, so it is necessary to evaluate the cost-effectiveness of each policy. In the present study, enforcement by means of an unmanned over-speed enforcement system, the enforcement effect of which was proven good compared to the cost required for traffic enforcement, is compared with enforcement by policemen. As a result of the comparison, the average speed was 82.66 km/h before the use of unmanned systems and policemen; the average speed with manned enforcement was 70.57 km/h; and the average speed with unmanned systems was 67.85 km/h. The speed limit violation rate was 65% before the use of unmanned systems and policemen; 32% with manned enforcement; and 15% with unmanned systems. Considering the kinds of vehicles, the average speed and violation rate were highest among private cars, then vans, and then trucks.. Considering lanes. The accident rate was estimated based on the above results, and the input cost-to-advantage was estimated. The annual cost-to-advantage was estimated by comparing the above estimated values with the conditions before the unmanned over-speed enforcement system. Subsequently, the enforcement by policemen showed a negative advantage of 76,130,590 won, and the enforcement by the unmanned system showed a positive advantage of 38,577,670 won.

• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.489-498
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• 2016

The objective of this study is to develop road traffic accident model involving child pedestrian especially at school zones and its surrounding area. The analysis is based upon traffic accident data collected near sixty elementary schools in City of Cheongju during 2012 and 2014. This study results in two statistical models ; one is to predict the number of road traffic accidents involving children, and the other is to predict EPDO(Equivalent Prperty Damage Only). These models are represented as Poisson models. which are statistically significant with the likelihood ratios of 0.533 and 0.273. The common explanatory variables of these models are the ratio of road section with more than 4 lanes, the number of entrance and exit, the number of signalized crosswalk in school zone, the number of school zone signage including road surface marking, and the number of speed limit signs. The specific variables are the length of road stretch in school zone, the number of reflector mirrors, and the number of signalized crosswalk outside school zone. It is concluded that these types of road safety facilities can reduce the number of traffic accidents involving children at school zones and its surrounding area.

• Journal of Korean Society of Transportation
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• v.19 no.2
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• pp.89-98
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• 2001

The objective of this Paper is to derive an adjustment factor for the presence of heavy vehicles when estimating capacity at unsignalized intersections (and/or at modern roundabouts). According to the 1997 and 2000 Highway Capacity Manual (HCM), potential capacity in such cases is estimated by simply adjusting base critical gap and base follow-up time. However, the procedure suggested in the HCM may lead to some errors in the adjustment, hence resulting in poor evaluation and design for the intersections, because it determines the value of adjusting factors by only the number of lanes on main streets regardless of the types of heavy vehicles. This paper shows a simple formula for making the adjustment. This formula is much like the HCM formula used for heavy vehicles in estimating highway capacity by the adoption of passenger car units (PCU). In contrast to the traditional approaches seen in the HCM, the PCU value of this case is explicitly expressed by the flow rate in the major streams and the gap difference in critical gaps chosen by passenger cars and particular heavy vehicles. Computational results of the adjustment factor are graphically illustrated.

• Journal of Korean Society of Transportation
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• v.32 no.2
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• pp.93-105
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• 2014

This study evaluated the relative efficiency of mobile emission reduction countermeasures through a Data Envelopment Analysis (DEA) approach and determined the priority of countermeasures based on the efficiency. Ten countermeasures currently applied for reducing greenhouse gases and air pollution materials were selected to make a scenario for evaluation. The reduction volumes of four air pollution materials(CO, HC, NOX, PM) and three greenhouse gases($CO_2$, $CH_4$, $N_2O$) for the year 2027, which is the last target year, were calculated by utilizing both a travel demand forecasting model and variable composite emission factors with respect to future travel patterns. To estimate the relative effectiveness of reduction countermeasures, this study performed a super-efficiency analysis among the Data Envelopment Analysis models. It was found that expanding the participation in self car-free day program was the most superior reduction measurement with 1.879 efficiency points, followed by expansion of exclusive bus lanes and promotion of CNG hybrid bus diffusion. The results of this study do not represent the absolute data for prioritizing reduction countermeasures for mobile greenhouse gases and air pollution materials. However, in terms of presenting the direction for establishing reduction countermeasures, this study may contribute to policy selection for mobile emission reduction measures and the establishment of systematic mid- and long-term reduction measures.

• Journal of Korean Society of Transportation
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• v.27 no.2
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• pp.107-115
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• 2009

Traffic islands were introduced for drivers and pedestrians to use the road in a safe and orderly way and were also a specified zone between traffic lanes to divide conflicting traffic flows and to provide pedestrian refuge. However, existing research and relevant standards described its purpose and effects only but not a safety standard to decide whether the traffic island warranted. This study was to introduce a parameter which had a high relationship with accidents by analyzing road and traffic conditions and traffic accident data at urban intersections. Based on the relationship between the parameter and the traffic accidents at the intersection, a pedestrian accident probability model was made by using a logit model. In addition, the study reviewed a pedestrian accident probability corresponding to traffic volume and size of the intersection during design of the intersection and then suggested the effectiveness of the traffic island in terms of traffic safety. In conclusion, when a large-scale intersection has significant traffic volumes, a high probability of traffic island-induced pedestrian accidents appears, while in the case of small volumes, the probability is low. Targeted design and operations of a traffic islands is necessary, because its introduction itself does not enhance pedestrian safety in all cases at all intersections. This study can be a useful reference for further development to set up a scheme of the traffic islands in terms of traffic safety.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.12
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• pp.1353-1359
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• 2007

Water quality constituents, and particle size distributions were characterized in urban bridge road runoff, Bridge road runoff contains significant loads of micro-particles, heavy metals and organic constituents. Bridge road runoff was monitored on four sites of four and six lanes bridge road areas along with traffic volume. A total seven storm events were monitored to characterize the bridge road runoff. The quantity of road runoff and quality constituents, including chemical oxygen demand(COD), suspended solids(SS), total nitrogen(T-N), ortho-phosphorus$(PO_4-P)$, total phosphorus(T-P), and particle size distribution were analyzed. The results indicate that the concentrations of SS, COD, T-N and T-P ranges were $35\sim2,390$ mg/L, $40\sim1,274$ mg/L, $0.03\sim21.25$ mg/L, and $0.05\sim4.58$ mg/L, respectively. And the results showed that the mean range of particle size and $D_{90}$ for bridge road runoff were $4.75\sim14.05{\mu}m$ and $17.33\sim58.15{\mu}m$, respectively.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.35-44
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• 2003

Considering possible legal and policy problems with regard to the Cheju Strait, a central issue is whether the Cheju Strait should be treated as Korean territorial sea or an international strait The claim that the strait is territorial sea has been based on the use of a straight baseline method of dermarcation With the use of straight baseline, Korea claims that the breadth of the Cheju Strait is only 20.7 miles at its narrowest point and therefore the strait becomes the territorial sea of Korea. The consideration cf marine pollution has weighed heavily in claiming the Cheju Strait as territorial sea. Pollution resulting from the accidents cf tankers caused by fire, collision, or stranding in the Cheju Strait and the Korea Strait would be enormous, affecting the entire coastal waters of the south coasts cf Korea's mainland and Japan's Tsushima Islands areas. Catastrophic pollution in the Cheju Strait could also come from the accidents cf large-size oil tankers passing through the Korea Strait from the Malacca Strait Although the Korean government considers the geographic and socioeconomic conditions sufficient to justify Korea's claim of the Cheju Strait as territorial sea, it believes that declaring it so would raise considerable legal conflicts with maritime states. In view of the legal difficulties and the need to meet the problems arising from the growing vessel traffic in the Cheju Strait, the sea lanes and traffic separation schemes may be considered an alternative to the internationalization of the Cheju Strait Even if the Korean government dose not do so, the regime of innocent passage should be applied to vessels passing through the Strait and should not suspend innocent passage through the Strait. Therefore, the Korean government needs to have a more legal, pragmatic, functional and managerial approach than a purely sovereign and selfish approach to the solution of legal matters of the Cheju strait For this purpose, the UN Convention on the Law of the Sea would serve as a guide and also self-restraint and cooperative approaches would become norms governing the resolution of the law of the sea issues in the Cheju Strait.