• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2184-2196
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• 1998

Admission control is one of the most important congestion control mechanism to be executed at the call set up phase by regulating traffic into a network in a preventive way. An efficient QOS evaluation or bandwidth estimation method is required for call admission to be decided in real time. In this paper, we spropose a computtionally simple approximation method of estimating cell loss probability and mean cell delay for admission control of both delay sensitive and loss sensitive calls. Mixed input queueing system, where a new call combines with the existing traffic, is used as a queueing model for QOS estimation. Also traffic parameters are suggested to characterize both a new call and existing traffic. Aggregate traffic is approximated by a renewal process with these traffic parameters and then mean delay and cell loss probability are detemined using appropriate approximation formulas. The accuracy of this approximation approach is examined by comparing their results with exact analysis or simulation results of vrious mixed unput queueing systems. Based on this QOS estimation method, call admission control scheme which is traffic independent and computable in yeal time are proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.487-493
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• 2017

The main purpose of this study is to evaluate the main parameters involved in the asphalt pavement distresses, including IRI (International Rough Index), fatigue, and permanent deformation. The main parameters are the region (Seoul and Busan), traffic level, asphalt binder, maximum aggregate of surface course, thickness of the surface course and base. A total of 64 case studies were carried out under the auspices of the KPRP (Korea Pavement Research Program). From the analysis of the KPRP test results, the key factors for the asphalt pavement distress were determined. Considering the effect of one variable in the basic condition, asphalt binder was the major factor having an effect on the distresses for an AADT (Annual Average Daily Traffic) of 5000 in the Seoul area. Among the remaining factors, the results were found to be in the order of the base layer thickness (A), surface layer thickness (B), and aggregate particle size thickness (D). The same results were obtained for an AADT of 10000. In the case of Busan with an AADT of 5000, the same result was obtained as for Seoul. Among the remaining factors, the results were in the order of the base layer thickness (A), aggregate particle thickness (D), and surface layer thickness (B). Even though there was a slight difference in the effect of the traffic level and region, asphalt binder was the parameter having the greatest effect on the asphalt pavement distress. In the case where the effect of multiple parameters was analyzed, the combination of the asphalt binder and base thickness showed a relatively strong effect.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5B
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• pp.491-497
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• 2004

In this Paper, we W a Hovel global traffic control architecture to isolate malicious network attacks and protect network infrastructure in Internet backbone networks. Unlike existing methods based on individual packets or flows, since the proposed detection and control methods are operated on the aggregate traffic level, the computational complexity can k significantly reduced, and they are applicable to develop a global defense architecture against network attack. Experimental results show that the proposed scheme can detect the network attack symptoms very exactly and quickly and protect the network resources as well as the normal traffic flows very efficiently.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.203-213
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• 2021

A vehicle crash occurs due to various factors such as the geometry of the road section, traffic, and driver characteristics. A safety performance function has been used in many studies to estimate the relationship between vehicle crash and road factors statistically. And depends on the purpose of the analysis, various characteristic variables have been used. And various characteristic variables have been used in the studies depending on the purpose of analysis. The existing domestic studies generally reflect the average characteristics of the sections by quantifying the traffic volume in macro aggregate units such as the ADT, but this has a limitation that it cannot reflect the real-time changing traffic characteristics. Therefore, the need for research on effective aggregation units that can flexibly reflect the characteristics of the traffic environment arises. In this paper, we develop a safety performance function that can reflect the traffic characteristics in detail with an aggregate unit for one hour in addition to the daily model used in the previous studies. As part of the present study, we also perform a comparison and evaluation between models. The safety performance function for daily and hourly units is developed using a negative binomial regression model with the number of accidents as a dependent variable. In addition, the optimal negative binomial regression model for each of the hourly and daily models was selected, and their prediction performances were compared. The model and evaluation results presented in this paper can be used to determine the risk factors for accidents in the highway section considering the dynamic characteristics. In addition, the model and evaluation results can also be used as the basis for evaluating the availability and transferability of the hourly model.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.2
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• pp.134-141
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• 1998

Sometimes we need to acquire symbolic quantity of information instead of physical quantity for the output of any system. For instance we can not control traffic signal accurately through only the number of vehicles. At that case we can produce better output using symbolic quantity of road length and width and vehicle type. But it is very difficult to aggregate symbolic information from the unrelated and mutually conflicted input after calculating linear and related expression. Moreover that will take much time to produce symbolic output by the physical quantity only. In this paper we implemented the ultimate traffic control information by using fuzzy sensor algorithm and compared our results with the conventional traffic controller after studying the necessity of symbolic information in the traffic control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.227-233
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• 2020

The demand for porous asphalt mixtures is increasing because it has a range of functions, such as reducing traffic accidents and traffic noise. On the other hand, its application is delayed due to concerns about durability. This study examined the effects of the maximum aggregate size, temperature, and porosity of an asphalt mixture on the durability. To this end, the durability measure was set to the Cantabro loss rate. Mixtures having the same porosity of 20% and the maximum aggregate diameters of 13 mm, 10 mm, and 8 mm were tested at 20℃ and -20℃. Mixtures containing 20% and 22% voids with the same material having the same diameter were tested. With 20% porosity, there was no significant difference in durability when there was a change in the maximum aggregate size. There was a significant difference between 20℃ and -20℃, but no significant difference in durability when there was a 2% difference between 20% and 22%. The significance of this study is that the durability was presented quantitatively by tests and statistical analysis. This research will help improve the durability of porous asphalt mixtures by evaluating the factors affecting the durability quantitatively.

• International Journal of Concrete Structures and Materials
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• v.11 no.1
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• pp.85-97
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• 2017

Research has suggested that conventional lightweight concrete can offer durability advantages due to reduced cracking tendency. Although a number of publications exist providing the results of laboratory-based studies on the durability performance of lightweight concrete (with lightweight coarse aggregate) and internally cured concrete (using prewetted lightweight fine aggregate), far fewer field studies of durability performance of conventional lightweight concrete bridge decks in service have been performed. This study was commissioned to provide insight to a highway agency on whether enhanced durability performance, and therefore reduced maintenance and longer lifecycles, could be anticipated from existing lightweight concrete bridge decks that were not intentionally internally cured. To facilitate performance comparison, each lightweight bridge deck selected for inclusion in this study was paired with a companion normalweight bridge deck on a bridge of similar structural type, deck thickness, and geometric configuration, with similar age, traffic, and environmental exposure. The field-observed cracking of the decks was recorded and evaluated, and crack densities for transverse, longitudinal, and pattern cracking of the normalweight and lightweight deck in each pair were compared. Although some trends linking crack prevalence to geographic location, traffic, and age were observed, a distinct difference between the cracking present in the paired lightweight and normalweight bridge decks included in this study was not readily evident. Statistical analysis using analysis of covariance (ANCOVA) to adjust for age and traffic influence did not indicate that the type of concrete deck (lightweight or normalweight) is a statistically significant factor in the observed cracking. Therefore, for these service environments, lightweight decks did not consistently demonstrate reduced cracking.

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.11-18
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• 2008

In recent, lots of researches for mechanical-empirical design concept for asphalt pavement are on going. AASHTO 2002 Design Guide in USA and KPRP(Korean Pavement Research Program) in Korea are under developing. In these programs, the mechanical properties of hot mix asphalt are a key role for design and analysis. Unfortunately, there is no proper database on the mechanical properties of hot mix asphalt, such as dynamic modulus. The use of dynamic modulus has couple of good advantages which is based on temperature, traffic loading and frequency on pavement. In this research, the verification of the relationship between maximum nominal aggregate size and dynamic modulus has been carried out. Also, test specimen size effect on dynamic modulus has been conducted. Considering the limitation of laboratory testing machine in Korea, test specimen with 100mm diameter and 150mm height is recommended for dynamic modulus test. Also, as the maximum nominal aggregate size increases, the dynamic modulus of hot mix asphalt increases.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.677-682
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• 2000

Porous concrete is defined as d type of concrete for which the fine aggregate component the matrix is entirely omitted. Although it had been used as a building material in Europe for over 60 years, low strength and high void ratio limited its application in the past. In recent years, however high void ratio of concrete has been recognized again and can be used as an environmental conscious material, for example, parking lots, draining light-traffic-volume pavements and as sea water purifying material. The result of an experiment on the void ratio of fiber reinforced porous concrete and its influence on the compressive strength and permeability relationship of concrete are reported in this paper. One-sized coarse aggregate of 5-10mm, and three absolute content of fiber(steel fiber, polyprophylen fiber) were used. The result of measured void ratio, permeability coefficient and compressive strength show a small variation. Void ratio, permeability coefficient and compressive strength of fiber reinforced porous concrete depend on contents of fiber and absolute volume ratios of paste to aggregate.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.3
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• pp.273-283
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• 2000

In this paper we suggest an optimal design method of Fuzzy-Neural Networks(FNN) model for complex and nonlinear systems. The FNNs use the simplified inference as fuzzy inference method and Error Back Propagation Algorithm as learning rule. And we use a HCM(Hard C-Means) Clustering Algorithm to find initial parameters of the membership function. The parameters such as parameters of membership functions learning rates and momentum weighted value is proposed to achieve a sound balance between approximation and generalization abilities of the model. According to selection and adjustment of a weighting factor of an aggregate objective function which depends on the number of data and a certain degree of nonlinearity (distribution of I/O data we show that it is available and effective to design and optimal FNN model structure with a mutual balance and dependency between approximation and generalization abilities. This methodology sheds light on the role and impact of different parameters of the model on its performance (especially the mapping and predicting capabilities of the rule based computing). To evaluate the performance of the proposed model we use the time series data for gas furnace the data of sewage treatment process and traffic route choice process.