• Nuclear Engineering and Technology
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• v.24 no.3
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• pp.297-310
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• 1992

FLECHT SEASET unblocked forced reflood tests are assessed using Apollo version of RELAP5/MOD3 5M5. The main purpose of the study is to examine the code predictability under forced reflood conditions having different initial power levels and flooding rates. Among various test matrices, the assessment calculations are performed for the test numbers 31701 31302, 31203, 31805, 34524, 31021, 34006 and 35807 These have been selected because they have similar initial conditions but different initial peak rod powers or flooding rates. In addition, various sensitivity calculations are performed for test number 31203 on the improved models of RELAP5/MOD3. Those are for the effect of Counter Current Flow Limit (CCFL) option at the outlet junction of the test section, for the effect of grid modelling on the interfacial drag calculations as well as on the heat structure calculations, and for the effect of nodalization and the time step size. The results of sensitivity studies show that the improved models of RELAP5/MOD3 enhance the code predictability. The assessment results show that the RELAP5/MOD3 has a tendency to underpredict the turn around temperature and the turn around time. But RELAP5/MOD3 silghtly overpredicts the turn around temperature for high flooding rate. The results also show that the calculated quenching by RELAP5/MOD3 is delayed with the increase of the rod power or the decrease of the flooding rate.

• International Journal of Highway Engineering
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• v.19 no.2
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• pp.153-165
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• 2017

PURPOSES : With the increasing number of older drivers in an aging society, there is a growing need for research and planning on traffic safety for the older drivers using an improved road geometry design. This study also proposed a modified urban road interchange design, which aims to keep the older drivers away from accident-prone and high-traffic areas of the city. METHODS : In this study, we examined accident data records of older drivers to identify accident-prone zones and intersections; we studied the road geometry at these zones and analyzed if it was an underlying cause for higher number of accidents. Based on the research and subsequent analysis, we suggested plans for improvement of road geometry design at these intersections. RESULTS :By studying historic data and analyzing factors that affect the likelihood of accidents of vehicles driven by older drivers and after studying suitable traffic accident prediction models, we identified the major variables that need to be modified at accident-prone intersections, such as the width of a left turn lane at an intersection and the radius of the right turn lane at a street corner. The results have a significance probability of less than 0.001 and a 95% confidence level. To improve safety at the identified intersection, this study suggests the installation of a left-turn-lane-shaped Positive Offset and a right-turn-lane-shaped Slip Lane concept and an adjustment of intervals between intersections.

• Journal of Science and Technology Studies
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• v.12 no.2
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• pp.33-79
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• 2012

This paper first aims to reveal that, in the current trend of 'the participatory turn' in STS, there are divergent positions subtly different from each other, and that the understanding of these divergent positions can be significant to study the differences, similarities and interfaces between the various models of scientific governance discussed in STS and those in risk governance developed by risk studies. Secondly, this paper shows that theoretical differences among STS scholars on scientific governance and public participation goes back to the 1970s and 1980s, during which they first laid down the conceptual basis of STS. All ideas and theories have their own historicity. This article is about the 'historical epistemology' of the participatory turn of STS, and is to seek 'political epistemology' that can become a shared vision of STS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.623-626
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• 2005

Toward the practical applications, on operation of conduction-cooled HTS SMES at temperatures well below 77 K should be investigated, in order to take advantage of a greater critical current density of HTS and considerably reduce the size and weight of the system. Recently, research and development concerning application of the conduction-cooled HTS SMES that is easily movement are actively progressing in Korea. Electrical insulation under cryogenic temperature is a key and an important element in the application of this apparatus. Using multi wrapped copper by polyimide film for HIS SMES, the breakdown characteristics of models for turn-to-turn, that is surface contact model, were investigated under ac and impulse voltage at 77 K. A material that is Polyimide film (Kapton) 0.025 mm thickness is used for multi wrapping of the electrode. Statistical analysis of the results using Weibull distribution to examine the wrapping number effects on breakdown voltage under ac and impulse voltage in $LN_2$ was carried.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1566-1574
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• 2017

When the inter-turn short circuit (ITSC) fault occurs, the distortion of the magnetic field is serious. The motor loss variations of each part are obvious, and the motor temperature field is also affected. In order to obtain the influence of the ITSC fault on the motor temperature distribution, firstly, the normal and the fault finite element models of the permanent magnet synchronous motor (PMSM) were established. The magnetic density distribution and the eddy current density distribution were analyzed, and the mechanism of loss change was revealed. The effects of different forms and degrees of the fault on the loss were obtained. Based on the loss analysis, the motor temperature field calculation model was established, and the motor temperature change considering the loop current was analyzed. The influence of the fault on the motor temperature distribution was revealed. The sensitivity factors that limit the motor continuous operation were obtained. Finally, the correctness of the simulation was verified by experiments. The conclusions obtained are of great significance for the fault and high temperature demagnetization of the permanent magnet analysis.

• International Journal of Highway Engineering
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• v.19 no.5
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• pp.143-151
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• 2017

PURPOSES : The purpose of this study is to develop models of accidents occurring at circular intersections related to the time of day and night and driver gender, and to provide countermeasures for safer circular intersections. METHODS : Seventy intersections built before 2008 were surveyed for inclusion in the modeling. Traffic accident data from 2008 to 2014 were collected from the TAAS data set of the Road Traffic Authority. Sixteen variables explaining the accidents including geometry and traffic volume were selected from the literature and seven multiple linear regression models were developed using SPSS 20.0. RESULTS : First, the null hypotheses, that the number of traffic accidents are not related to driver gender or time of day, were rejected at a 5% level of significance. Second, seven statistically significant accident models with $R^2$ value of 0.643-0.890 were developed. Third, in daytime models by gender, when the right-turn-only lane was selected as the common variable, the number of lanes, presence of driveways and speed humps, diagrammatic exit destination sign, and total entering traffic volume were evaluated as specific variables. Finally, in nighttime models by gender, when the diagrammatic exit destination sign was selected as the common variable, total entering traffic volume, presence of right-turn-only lanes, number of circulatory road way lanes, and presence of splitter islands and driveways were identified as specific variables. CONCLUSIONS:This study developed seven accident models and analyzed the common and specific variables by time of day and gender. The results suggest approaches to providing countermeasures for safer circular intersections.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.145-153
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• 2008

Existing shortest-path algorithms mainly consider a single attribute. But traveler actually chooses a route considering not single attribute but various attributes which are synthesized travel time, route length, personal preference, etc. Therefore, to search the optimal path, these attributes are considered synthetically. In this study route searching algorithm which selects the maximum utility route using discrete choice model has developed in order to consider various attributes. Six elements which affect route choice are chosen for the route choice model and parameters of the models are estimated using survey data. A multinomial logit models are developed to design the function of route choice model. As a result, the model which has route length, delay time, the number of turning as parameter is selected based on the significance test. We use existing shortest path algorithm, which can reflect urban transportation network such as u-turn or p-turn, and apply it to the real network.

• International Journal of Control, Automation, and Systems
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• v.3 no.2
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• pp.173-182
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• 2005

In this paper, a target tracking algorithm for tracking maneuvering vehicles is presented. The overall algorithm belongs to the category of an interacting multiple-model (IMM) algorithm used to detect multiple targets using fused information from multiple sensors. First, two kinematic models are derived: a constant velocity model for linear motions, and a constant-speed turn model for curvilinear motions. Fpr the constant-speed turn model, a nonlinear information filter is used in place of the extended Kalman filter. Being equivalent to the Kalman filter (KF) algebraically, the information filter is extended to N-sensor distributed dynamic systems. The model-matched filter used in multi-sensor environments takes the form of a federated nonlinear information filter. In multi-sensor environments, the information-based filter is easier to decentralize, initialize, and fuse than a KF-based filter. In this paper, the structural features and information sharing principle of the federated information filter are discussed. The performance of the suggested algorithm using a Monte Carlo simulation under the two patterns is evaluated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.93-95
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• 2007

Studies on ski-end shape control at the top end of rolling plate in heavy thick plate mill by using FEM analysis and measuring system have been performed. Plate shape behaviour at the top-end on rolling by the two different methods in finishing rolling process has been observed. One is to minimize the height of ski-end by using pass line based on the relational model between shape factor and pick-up and the other one is to prevent turn down problem caused by the impact between table roller and down bended plate on rolling by using roll speed difference. To minimize the height of ski-end, the prediction models based on the FEM analysis and measuring data was developed. The control method of ski - end shape on finishing rolling process was applied in actual mill and the height of ski-end was reduced by about 50% compared with conventional operation.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1669-1674
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• 2004

In this paper, a nonlinear information filter (IF) for curvilinear motions in an interacting multiple model (IMM) algorithm to track a maneuvering vehicle on a road is investigated. Driving patterns of vehicles on a road are modeled as stochastic hybrid systems. In order to track the maneuvering vehicles, two kinematic models are derived: A constant velocity model for linear motions and a constant-speed turn model for curvilinear motions. For the constant-speed turn model, a nonlinear IF is used in place of the extended Kalman filter in nonlinear systems. The suggested algorithm reduces the root mean squares error for linear motions and rapidly detects possible turning motions.