• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.44-48
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• 2008

This paper describes on studies of the heavy duty engine calibration for better fuel economy based on real driving conditions. Using testbed validated software simulation of the engine and turbocharger system, an alternative turbocharger specification, with potential to improve fuel economy was identified. Secondly, the engine calibration was modified to optimize vehicle fuel economy over a typical customer drive cycle whilst still meeting the steady-state (testbed) emissions legislation. These results were confirmed by field testing of a vehicle equipped with the updated specifications. This study found good agreements between the prediction and the field test on the vehicle fuel economy improvements of the express bus with updated calibration and turbocharger.

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.841-846
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• 2006

This paper presents a numerical approach to optimizing vehicle fuel economy in a higway bus. The method described is based on using a commercial software vehicle simulation to identify the relative efficiency of each of the vehicle systems, such as the engine hardware, engine software calibration, transmission, cooling system and ancillary drives. The simulation-based approach offers a detailed understanding of which vehicle systems are underperforming and by how much the vehicle fuel economy can be improved if those systems are brought up to best-in-class performance. In this way, the optimum vehicle fuel economy can be provided to the vehicle customer. A further benefit is that the simulation requires only a minimum number of vehicle testing for initial validation, with all subsequent field test cycles performed in software, thereby reducing development time and cost for the manufacturer.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1957-1958
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• 2008

The Logic Built In Self Test (LBIST) technique is substantially applied in chip design in most many semiconductor company in despite of unavoidable overhead like an increase in dimension and time delay occurred as it used. Currently common LBIST software uses the MISR (Multiple Input Shift Register) However, it has many considerations like defining the X-value (Unknown Value), length and number of Scan Chain, Scan Chain and so on for analysis of result occurred in the process. So, to solve these problems, common LBIST software provides the solution method automated. Nevertheless, these problems haven't been solved automatically by Tri-state Bus in logic circuit yet. This paper studies the simulator and algorithm that judges whether Tri-state Bus lines is the circuit which have X-value or One-hot Value after presuming the control signal of the lines which output X-value in the logic circuit to solve the most serious problems.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.10-15
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• 2005

This study was initiated to evaluate the cooling performance of CAC (charged air cooler) and radiator in the engine room of a mini bus. So we had firstly to predict the mass flow rate coming from radiator grille and front bum per opening using computational fluid dynamics (CFD) simulation based on 3D configuration. And simulations were carried out for different cooling module layout and bum per opening hole size on sam e vehicle operating condition. Simulation results show that CAC cooling performance at reverse protecting plate-applying model was much efficient than that of the bum per opening hole size-increasing model in IMTD point of view. Part of the CFD simulation results was com pared to with experimental data. It was confirm ed that the CFD approach using STAR-CD based on pursuing no-com promise solution could provide design engineers with useful design information in the early design stage of vehicle development.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.16-21
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• 2005

The performance of reciprocating internal combustion engine is a strong function of the air intake system configuration. In order to improve engine power, it is essential to optimize the air induction system. In this study, a numerical investigation has been carried out for the three-dimensional flow and pressure characteristics in air intake system of a large-sized commercial bus. CFD simulations using STAR-CD were also perform ed to evaluate effects of intake duct geometry and structure variation inside air cleaner on the negative pressure distribution of overall intake system. Studies for improving the back pressure distribution have been proposed and quantitatively examined based on intensive case studies.

• Journal of the Korea Society of Computer and Information
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• v.22 no.7
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• pp.9-16
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• 2017

In this paper, we propose a development method of portable Automatic Test Equipment based on PXIe platform. Legacy VME form factor structured test equipment has limited reuse and expansion of modules due to unapplied bus specification. In particular, these limitations can cause development periods and costs to increase, and the reliability of environmental conditions is lacking due to non-standard modules. The test equipment of the proposed PXIe platform can use diverse COTS modules to shorten the development period and minimize the instability between developments. The PXIe development module works with standard Xilinx FPGAs, PXIe Windows device drivers, and applications on standard PXIe buses. The use of standard bus and COTS modules increases scalability and reusability, enabling rapid development and excellent maintenance. Through the test, we show the proposed test equipments can be implemented efficiently between the development processes and proved their reliability through function tests and environmental tests.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.181-185
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• 2006

A study to get better vehicle fuel economy is described based on an express bus. The approach is based on using a commercial software vehicle simulation to identify the relative efficiency of each of the vehicle systems, such as the engine hardware, engine software calibration, transmission, cooling system and ancillary drives. The simulation-based approach offers a detailed understanding of which vehicle systems are underperforming and by how much the vehicle fuel economy can be improved if those systems are brought up to best-in-class performance. In this way, the optimum vehicle fuel economy can be provided to the vehicle customer. A further benefit is that the simulation requires only a minimum of vehicle testing for initial validation, with all subsequent field test cycles performed in software, thereby reducing development time and cost for the manufacturer.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.621-631
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• 2017

In this paper, we study the various impacts of connecting distributed generation (DG) to the distribution network. The comprehensive evaluation index system (CEIS) of four hierarchies is established, considering economy, reliability and voltage quality, and the calculation methods of different indexes are presented. This paper puts forward an improved triangular fuzzy number analytic hierarchy process (ITFNAHP) to weight the second level indexes (SLI) and the third level indexes (TLI), and calculates the variation coefficient to weight the fourth level indexes (FLI). We calculate the comprehensive weight coefficients based on the weight coefficients of the SLI, TLI and FLI, and then calculate the comprehensive evaluation of satisfaction (CES) of different access schemes. On the basis of the IEEE 33-bus example system, simulations of the calculation methods and the comprehensive evaluation method are carried out under different DG access schemes according to the same total investment cost and the same permeability, respectively, and the simulation results are analyzed and discussed.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.119-127
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• 2009

It has been known that bus route and company related characteristics have influences on punctuality, but fewer research have been conducted. Independent variables used in this study were selected using correlation analysis, and OLS(Ordinary Least Square) and HLM(Hierarchical Linear Model) were employed to identify factors affecting bus punctuality(headway deviation). The results showed that ICC(intraclass Correlation Coefficient) is 0.10, indicating that hierarchical linear models are more adequate for these data because there is effective variation in the subjects between companies. Punctuality was found to be negatively associated with the number of vehicles, the number of persons per vehicle, and total travel time. On the other hand, average headway and company size have a positive relationship with punctuality. Therefore, the number of vehicles per route, average headway, and the number of vehicles managed by a company should be considered for more accurately evaluating the management of piunctuality.

• Korean Journal of Adult Nursing
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• v.23 no.4
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• pp.321-331
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• 2011

Purpose: This study was designed to identify the incidence risk of cardicerebrovascular disease (CVD) among male bus drivers, and to examine and compare the predictors of their health behavior according to the level of CVD incidence risk. Methods: The convenience sample of 222 male bus drivers were recruited from a bus company located in Jeonnam province. Data were collected from self-reported questionnaires and annual medical examination records from 2010. The CVD incidence risk was calculated based on the risk criteria for industrial workers. Results: The 26.6% and 26.1% of the participants were in the moderate and high risk group, respectively. The 72% of the participants were in the precontemplation stage and reported no intention to change their unhealthy lifestyles. Stepwise multiple regression analyses showed that current smoking, excessive alcohol drinking, physical inactivity and lack of knowledge were negative predictors of good health behavior in the normal/low risk group (Adj $R^2$=.443). Heavy alcohol drinking, current smoking, physical inactivity and dyslipidemia were reported by the moderate/high risk group (Adj $R^2$=.427). Conclusion: This study suggested that targeted education and counseling are needed to modify unhealthy lifestyles such as alcohol consumption, smoking and exercise among middle aged male drivers. Especially, dyslipidemia should be managed among those who are at risk for CVD.