• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.95-102
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• 2015

Recently, the maintenance activity for aging of bridge structures was difficult because of traffic jam, environment pollution and increasing cost. And to solve these problems, modular bridge research has been studied. After static and cyclic loading test was conducted for serviceability and bending performance with one way slab, effective moment of inertia of modular specimen was analyzed to estimate the deflection by KCI(2012). To conduct the test, one integral slab and three modular slabs were made for static loading and one integral and modular slab were made for cyclic. As a result of the test, the modular slab had the similar bending performance of the integral. But the ultimate deflection showed the insufficient which was smaller than 20%. In the cyclic loading test, the modular slab has different behavior of deflection with the integral, so it was evaluated difficult for serviceability. In addition, effective moment of inertia by KCI(2012) was not estimated for modular slab with connection. The new value of m which was ratio between moments is 4.53 based on result of test for predicting deflection of modular.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.1 no.1
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• pp.41-51
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• 2002

As Advanced Traveler Information System(ATIS) is the kernel of the Intelligent Transportation System, it is very important how to manage data from traffic information collectors on a road and have at borough grip of the travel time's change quickly and exactly for doing its part. Link travel time can be obtained by two method. One is measured by area detection systems and the other is estimated by point detection systems. Measured travel time by area detection systems has the limitation for real time information because it Is calculated by the probe which has already passed through the link. Estimated travel time by point detection systems is calculated by the data on the same time of each. section, this is, it use the characteristic of the various cars of each section to estimate travel time. For this reason, it has the difference with real travel time. In this study, Artificial Neural Networks is used for estimating link travel time concerned about the relationship with vehicle detector data and link travel time. The method of estimating link travel time are classified according to the kind of input data and the Absolute value of error between the estimated and the real are distributed within 5$\~$15minute over 90 percent with the result of testing the method using the vehicle detector data and AVI data of Namsan Tunnel $\#$1. It also reduces Time lag of the information offered time and draws late delay generation and dissolution.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.3
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• pp.188-194
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• 2008

In this paper, we propose for improving QoS in Hospital wireless network using Cellular-IP/PRC(Paging Route Cache) with Paging Cache and Route Cache in Cellular-IP and propose for performance of realtime and non-real time handoff service using Handoff state machine Paging Route Cache. Although the Cellular-IP/PRC technology is devised for mobile internet communication, it has its vulnerability in frequent handoff environment. This handoff state machine using differentiated handoff improves quality of services in Cellular-IP/PRC Suggested algorithm shows better performance than existing technology in wireless mobile internet communication environment. When speech quality is secured considering increment of interference to receive in case of suppose that proposed acceptance method grooves base radio station capacity of transfer node is plenty, and moat of contiguity cell transfer node was accepted at groove base radio station with a blow, groove base radio station new trench lake acceptance method based on transmission of a message electric power estimate of transfer node be. Do it so that may apply composing PC(Paging Cache) and RC(Routing Cache) that was used to manage paging and router in radio Internet network in integral management and all nodes as one PRC(Paging Router Cache), and add hand off state machine in transfer node so that can manage hand off of transfer node and Roaming state efficiently, and studies so that achieve connection function at node. Analyze benevolent person who influence on telephone traffic in system environment and forecasts each link currency rank and imbalance degree, forecast most close and important lake interception probability and lake falling off probability, GoS(Grade of Service), efficiency of cell capacity in QoS because applies algorithm proposing based on algorithm use gun send-receive electric power that judge by looking downward link whether currency book was limited and accepts or intercept lake and handles and displays QoS performance improvement.

• Journal of Korean Society of Rural Planning
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• v.22 no.2
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• pp.121-129
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• 2016

A disaster can be defined in many ways based on perspectives, in addition, its types are able to classify differently by various standards. Considering the different perspectives, the disaster can be occurred by natural phenomenon that is like typhoon, earthquake, flood, and drought, and by the accident that is like collapse of facilities, traffic accidents, and environmental pollution, etc. Into the modern society, moreover, the disaster includes the damages by diffusion of epidemic and infectious disease in domestic animals. The disaster was defined by natural and man-made hazards in the past. As societies grew with changes of paradigm, social factors have been included in the concept of the disaster according to new types unexpected by new disease and scientific technology. Change the concept of social disasters, Ministry of Public Safety and Security (MPSS) has provided the regional safety index, which measures the safety level of a local government. However, this regional safety index has some limitation to use because this index provides the information for city unit which is a unit of administrative districts of urban. Since these administrative districts units are on a different level with urban and rural areas, the regional safety index provided by MPSS is not be able to direct apply to the rural areas. The purpose of this study is to determine the regional safety index targeting rural areas. To estimate the safety index, we was used for 3 indicators of the MPSS, a fire, a crime, and an infectious disease which are evaluable the regional safety index using an accessibility analysis. For determining the regional safety index using accessibility from community centers to public facilities, the safety index of fire, crime, and infectious disease used access time to fire station, police office, and medical facility, respectively. An integrated Cheongju, targeting areas in this study, is mixed region with urban and rural areas. The results of regional safety index about urban and rural areas, the safety index in rural area is relatively higher than in the urban. Neverthless the investment would be needed to improve the safety in the rural areas.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.209-221
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• 2009

Travel time estimation under given traffic conditions is important for providing drivers with travel time prediction information. But the present expressway travel time estimation process cannot calculate a reliable travel time. The objective of this study is to estimate the path travel time spent in a through lane between origin tollgates and destination tollgates on an expressway as a prerequisite result to offer reliable prediction information. Useful and abundant toll collection system (TCS) data were used. When estimating the path travel time, the path travel time is estimated combining the link travel time obtained through a preprocessing process. In the case of a lack of TCS data, the TCS travel time for previous intervals is referenced using the linear interpolation method after analyzing the increase pattern for the travel time. When the TCS data are absent over a long-term period, the dynamic travel time using the VDS time space diagram is estimated. The travel time estimated by the model proposed can be validated statistically when compared to the travel time obtained from vehicles traveling the path directly. The results show that the proposed model can be utilized for estimating a reliable travel time for a long-distance path in which there are a variaty of travel times from the same departure time, the intervals are large and the change in the representative travel time is irregular for a short period.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.1
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• pp.85-93
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• 2015

Previous studies have estimated crash prediction models with the fixed effect model which assumes the fixed value of coefficients without considering characteristics of each intersections. However the fixed effect model would estimate under estimation of the standard error resulted in over estimation of t-value. In order to overcome these shortcomings, the random effect model can be used with considering heterogeneity of AADT, geometric information and unobserved factors. In this study, data collections from 89 intersections in Daejeon and estimates of crash prediction models were conducted using the random and fixed effect negative binomial regression model for comparison and analysis of two models. As a result of model estimates, AADT, speed limits, number of lanes, exclusive right turn pockets and front traffic signal were found to be significant. For comparing statistical significance of two models, the random effect model could be better statistical significance with -1537.802 of log-likelihood at convergence comparing with -1691.327 for the fixed effect model. Also likelihood ration value was computed as 0.279 for the random effect model and 0.207 for the fixed effect model. This mean that the random effect model can be improved for statistical significance of models comparing with the fixed effect model.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.2
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• pp.43-57
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• 2021

The Forward Collision Warning, a representative technology of the Advanced Driver Assistance Systems, was selected as the target technology. The cognitive response time, deceleration, and impact were selected as the measures of effectiveness. And the amount of change with and without the Forward Collision Warning was measured. The experimental scenarios included a sudden stop event (1) of the vehicle in front of the driver and an event (2) in which the vehicle intervened in the next lane. All experiments were divided into day and night. As a result of the analysis, response time and the deceleration rate decreased when the forward collision warning system was installed. It was analyzed that the driver's risk situation could be detected quickly and the number of front-end collisions could be reduced as a result. Reflecting the driver's operating habits and diversifying the experimental scenarios will increase the installation effectiveness of ADAS and be used to estimate the effectiveness of other technologies.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.1
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• pp.1-13
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• 2019

With commercial apps popular in EU, MaaS has been emerging around the globe as a new approach to worsening urban traffic problems. In contrast, it is still mainstay in Korea simply discussing the concept and necessities of MaaS, rather than seeking for real-world solutions for the commercialization. The purpose of this research is to analyze the demand-side i1mpacts of travel time and cost changes according to MaaS adoption, and to see its commercial feasibility in Korea. The 2010 KTDB traveler's nationwide OD data is used to estimate the level of fare discount for balancing the mode shift and fare revenue changes followed by MaaS implementation. The analysis results show that MaaS leads to the increase of public transport ridership as a result of the diminishing travel cost and time, and that the time saving works more positively for ridership increase. Also, the optimum level of fare discount is estimated 2.56% without damaging the revenue. This finding reveals that MaaS impact is superior to the other single-sided public transport inventive measures since it can affect both travel cost and time reduction at the same time.

• Korea Trade Review
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• v.43 no.5
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• pp.159-177
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• 2018

The container shipping sector is an important international logistics operation that connects open economies. Freight rates rapidly change as the market fluctuates, and staff related to the shipping market are interested in factors that determine freight rates in the container market. This study uses the Vector Error Correction Model(VECM) to estimate the impact of factors affecting container freight rates. This study uses data published by Clarksons. The analysis results show a 4.2% increase in freight rates when world container traffic increases at 1.0%, a 4.0% decrease in freight rates when volume of container carriers increases by 1.0%, a 0.07% increase in freight rates when bunker price increases by 1.0%, and a 0.04% increase in freight rates accompanying 1.0% increase in libor interests rates. In addition, if the current freight rate is 1.0% higher than the long-term equilibrium rate, the freight rate will be reduced by 3.2% in the subsequent term. In addition, if the current freight rate is 1.0% lower than the long-term equilibrium rate, the freight rate will decrease by 0.12% in the following term. However, the adjusting power in a period of recession is not statistically significant which means that the pressure of freight rate increase in this case is neglectable. This research is expected to contribute to the utilization of scientific methods in forecasting container freight rates.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1D
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• pp.1-10
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• 2008

Recently, the Seoul Metropolitan Government (SMG) has initiated several urban redevelopment projects to revitalize the downtown well equipped for transit oriented development (TOD). Since, TOD should incur higher density development in our context, it has negative impacts on travel patterns, congestion, and urban environmental quality. The purpose of this study is to develop new transportation service index which can facilitate higher density TOD. This study includes relevant foreign case studies, the development of multimodal transportation index, and the impact analysis of TOD when it is applied in the downtown Seoul. In chapter III, it developed a so-called ITLOS, new multimodal transportation service index which shows the possibility of accommodating further development by integrating roadway service index with public transportation service index. The study sets ten policy scenarios by varying densities, and run the Seoul Congestion Management Model (SECOMM) to estimate the sustainable transportation impacts of TOD in the downtown. Travel speed index that only represents the availability of road capacity for development reveal that higher density development in the downtown can deteriorate traffic congestion while improving region-wide transportation level of service in Seoul. Also, it is proved that higher density development is more feasible when using ITLOS as the index because it considers not only available road capacity but subway capacity in the analysis area.