• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.201-205
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• 2001

This paper presents the load modeling process and bus load models for KEPCO power system. At first, load devices commonly used in KEPCO power systems were selected, and tested for measuring the voltage and frequency sensitivity of active and reactive power. From this test, about 40 voltage and frequency dependent load models have been obtained. The bus load composition rate for KEPCO power system has been determined using the various recent surveys and papers in order to develop the load model for a power system bus. To verify the accuracy of developed bus load models, the field test for measuring active and reactive power according to artificial variation of the bus voltage was performed at 8 substations for spring summer, autumn, winter cases. With data of this seasonal field test, more reliable bus load models for KEPCO power systems were developed.

• Journal of Korean Society of Transportation
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• v.29 no.2
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• pp.15-24
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• 2011

This study discusses an equity analysis performed to supplement the existing bus service evaluation system. The equity of 179 feeder bus routes in the city of Seoul(Year 2009) is analyzed by employing the modified BCC model along with the desirable inputs such as a number of bus stops and a frequency of operations. In the analysis, each DMU (Decision Making Unit) is assumed to use the desirable inputs, and produces both the index of equity and the index of accessibility. We apply an input-oriented modified BCC model to analyze the equity of the DMUs. The computational result indicates that only 9% of the feeder bus routes are equitable among the total DMUs and the average equity estimate is 0.702. It is also suggested that on average approximately 60% increases of desirable inputs (i.e., a number of bus stops and a frequency of operations) are needed in order to improve equity of DMU in the city of Seoul. The result of the tobit regression analysis on the determinant factors affecting the equity of DMUs shows that all the independent variables (i.e., a number of bus stops and a frequency of operations) are statistically significant at 5% significance level, and the number of bus stops is found to be the most influential factor.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.5
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• pp.80-86
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• 2010

The conventional bus system architecture consists of masters, slaves, arbiter, decoder and so on in shared bus. As several masters can't use a bus concurrently, arbiter plays an role in arbitrating the bus. The efficiency of bus usage can be determined by the selection of arbitration method. Fixed Priority, Round-Robin, TDMA and Lottery arbitration policies are studied in the conventional arbitration method where the bus priority is primarily considered. In this paper, we propose the arbitration method that calculates the bus utilization of each master. Furthermore, we verify the performance compared with the other arbitration methods through TLM(Transaction Level Model). From the results of performance verification, the arbitration methods of Fixed Priority and Round-Robin can not set the bus utilization and those of TDMA and Lottery happen the error of 50% and 70% respectively compared with bus utilization set by user in more than 100,000 cycles. On the other hand, the bandwidth-award bus arbitration method remains the error of less than 1% since approximately 1000 cycles, compared with bus utilization set by user.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.31-38
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• 2010

Bus manufacturers have tested and studied the dynamic collapse behavior of a bus body structure in rollover since UN ECE established ECE Regulation 66 to provide the requirement for the strength of bus structure. In spite of the costly cycles of practical tests, however, it is still a hard task to meet the rollover regulation by means of local reinforcements in the bus structure. Therefore it is necessary to develop a well designed strategy for the rollover strength implemented in the early stage of vehicle development. In this study, the suitable development method for each design stage from a component to complete body structure was considered to make a well-established development process of a bus body structure for rollover safety. For the efficient approach of the concept design stage, a numerical model based on the plastic hinge theory was used instead of detailed shell models. After setting up the concept design for the component size and geometry, the shell model was used to confirm and optimize the whole structure composition. The process developed in this study was practically used as an effective method to predict the rollover behavior of a new bus body structure.

• Journal of Korean Society of Transportation
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• v.33 no.6
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• pp.543-553
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• 2015

This study analyzed that the impact of the bus use environment on users' stress in each step of bus use, from accessing to leaving to transfer, in the city of Daejeon. For this, we collected the stress data from 300 users using personal interviews at the bus stops and on-board bus. Also, we used factor analysis and structural equation model method for analysis of the impact of external and internal bus environments on stress of users. The results of this study showed that the highest stress impact factor was an onboard factor(${\beta}=.416$) including 'density and crowding', 'no seat to seat' and 'low ride comfort and safe'. The next stress impact factor was transfer factor including 'insufficient transfer information', 'lack of connectivity of bus and subway' and 'uncomfort transfer route'. From the above, we recommend that bus policies need to focus on not the supplier but users and also, this user based policy need to be more specified considering the characteristics of various users such as females, the elderly, irregular users, and so on.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.217-228
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• 2021

After the integrated fare system has been applied, public transportation and transfer traffic increased. As a result, transfer passengers must be considered in the operation of the bus. Although previous studies have limitations due to utilizing deterministic mathematical models, which fails to reflect the stochastic movements of passengers and buses, in this study, a more realistic bus stop micro-simulation model is proposed. Based on the proposed simulation model, we represent the relationship between bus arrival interval and passenger wait time as a regression model and empirically show the differences between the cases with and without transfer passengers. Also, we propose a method converting passenger waiting time to cost and find optimal bus arrival interval based on the converted cost. It is expected the proposed method enables bottom-up decision making reflecting practical situation.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.1
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• pp.41-46
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• 2014

Bus service is easily adjusted to accommodate the changed demand. Despite the flexibility of that, its relocation should overcome the following problems: first, Bus line rearrangement should consider the balance between the demand and the supply to enhance the transit equity among the users scattered around the area that supply against demand imbalances. Second, the existing demand analysed is to crude since the demand was analysed based on TAZ. mainly based on the Dong unit. Utilization of the GWR and GIS-T data can resolve the problem. In this paper, the limitation of the conventional transit demand analysis model is overcome by deploying the GWR model which identifies the transit demand based on the geographic relation between the service location and those of the users. GWR model considers the spatial effect of the bus demand in accordance with the distance to the each bus stops using SCD(Smart Card Data) and BIS(Bus Information System). This demand map was then superimposes with the existing bus route which identified the areas where the balance between demand and supply is severly skewed. since the analysis was computed with SCD and BIS at every bus stops. the shortage and surplus of bus service of entire study area could computed. Further. based on this computational result and considering the entire bus service capacity data. Bus routes optimization from the oversupplied areas to the undersupplied area was illustrated thus this study clearly compared the benefits the GIS.

• Journal of Korean Society of Transportation
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• v.5 no.2
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• pp.5-18
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• 1987

Buses arrive at a traffic intersection later than passenger cars by the amount of dwell time at previous bus stops. This late arrival of buses affects the total passenger delay at intersections especially in the street carrying large bus volume. The bus progression signal system in which the signal offset is given in favor of bus platoons was applied in the case area of Kangnam street in Seoul, and various effects were analyzed using the TRANSYT-7F simulation model. It was observed that the total passenger delay can be reduced significantly if the bus progression signal system is applied, and the most effective bus priority treatment is proved to be the bus progression signal system installed with exclusive bus lanes.

• Journal of Korean Society of Transportation
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• v.18 no.2
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• pp.7-16
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• 2000

This study Presents an guideline of the exclusive bus and/or truck lane on 8 lanes freeways using FREFLO model and INTEGRATiON model. Four alternatives : do nothing, bus exclusive lane, truck exclusive lane, bus and truck exclusive lane, were evaluated using average daily vehicle travel time as measures of effectiveness. It is found that bus and truck exclusive lane is the most effective alternative reducing total travel time by 7% when ADT is below 80,000 vehicle/day. However, when ADT is above 80,000 vehicle/day and bus Proportion is above 12%, bus exclusive lane is the most effective alternative reducing total travel time by more than 5.6%. It is further found that INTEGRATION, the stochastic and microscopic model, is more sensitive than FREFLO, the deterministic and macroscopic model, in evaluating the effectiveness of four alternatives.

• The Journal of the Korea Contents Association
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• v.7 no.11
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• pp.84-93
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• 2007

This paper presents a methodology that accelerates estimating the system-level power consumption for on-chip bus of SoC platforms. The proposed power modeling can estimate the power consumption according to the change of a target SoC system. The proposed model comprises two parts: the one is power estimation of bus logics reflecting the architecture of the bus such as the number of bus layers, the other is to estimate the power consumed by the bus lines during data transmission. We designed the target multimedia SoC system, MPEG encoder as an example and evaluated power consumption using this model. The simulation result shows that the accuracy of the proposed model is over 92%. Thus, the proposed power model can be used to design of a high-performance/low-power multimedia SoC.