• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.437-448
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• 2016

Some previous researches suggested a transit trip destination inference method by constructing trip chains with incomplete(missing destination) smart card dataset obtained on the entry fare control systems. To explore the feasibility of the transit trip destination inference method, the transit trip chains are constructed from the pre-paid smart card tagging data collected in Busan on October 2014 weekdays by tracing the card IDs, tagging times(boarding, alighting, transfer), and the trip linking distances between two consecutive transit trips in a daily sequences. Assuming that most trips in the transit trip chains are linked successively, the individual transit trip destination zones are inferred as the consecutive linking trip's origin zones. Applying the model to the complete trips with observed OD reveals that about 82% of the inferred trip destinations are the same as those of the observed trip destinations and the inference error defined as the difference in distance between the inferred and observed alighting stops is minimized when the trip linking distance is less than or equal to 0.5km. When applying the model to the incomplete trips with missing destinations, the overall destination missing rate decreases from 71.40% to 21.74% and approximately 77% of the destination missing trips are the single transit trips for which the destinations can not be inferable. In addition, the model remarkably reduces the destination missing rate of the multiple incomplete transit trips from 69.56% to 6.27%. Spearman's rank correlation and Chi-squared goodness-of-fit tests showed that the ranks for transit trips of each zone are not significantly affected by the inferred trips, but the transit trip distributions only using small complete trips are significantly different from those using complete and inferred trips. Therefore, it is concluded that the model should be applicable to derive a realistic transit trip patterns in cities with the incomplete smart card data.

• Journal of the Korean earth science society
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• v.39 no.3
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• pp.291-302
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• 2018

The purpose of this study is to investigate pre-service middle school earth science teachers' perceptions about the learning of geological field trip. The study sample consists of 39 undergraduate students at the university located in a metropolitan city. Additionally, 4 pre-service earth science teachers are semi-structure interviewed. The instrument of the study includes a 5-category perception about the learning of geological field trip, which consists of needs, educational values, educational experience, teaching methods, and training for learning. The results are as follows. First, participants are important to the need and educational values of learning about the geological field trip regardless of gender and grade level. Second, all participants have experienced geological field trip in college. They have more opportunities to experiment for field trip as they advance to higher grade. There is significant difference between lower and higher graders in terms of the goal of learning about geological field trip. It needs a new lesson model to teach geology between men and women regarding teaching methods category. In order to practice geological field trip in school, participants perceive that they need the knowledge of geological context, experiment of field trips, and how to teach geological field trip to students. This study suggests that pre-service earth science teachers' perceptions include how to teach and learn geological field trip during their college year.

• Nuclear Engineering and Technology
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• v.27 no.2
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• pp.203-215
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• 1995

A continued operation of RCPs during a certain small break LOCA may increase unnecessary inventory loss from the RCS causing a severe core uncovery which might lead to a fuel failure. After TMI-2 accident, the CEOG developed RCP trip strategy called “Trip-Two/Leave-Two” (T2/L2) in response to NRC requests and incorporated it in the generic EPG for CE plants. The T2/L2 RCP trip strategy consists of tripping the first two RCPs on low RCS pressure and then tripping the remaining two RCPs if a LOCA has occurred. This analysis determines the RCP trip setpoint and demonstrates the safe operational aspects of RCP trip strategy during a small break LOCA for YGN 3&4. The trip setpoint of the first too RCPs for YGN 3&4 is calculated to be 1775 psia in pressurizer pressure based on the limiting small break LOCA with 0.15 ft$^2$ break size in the hot leg. The analysis results show that YGN 3&4 can maintain the core coolability even if the operator fails to trip the second too RCPs or trips at worst time. Also, the YGN 3&4 RCP trip strategy demonstrates that both the 10 CFR 50.46 requirements on PCT and the ANSI standards 58.8 requirements on operator action time can be satisfied with enough margin. Therefore, it is concluded that the T2/L2 RCP trip strategy with a trip setpoint of 1775 psia for YGN 3&4 can provide improved operator guidance for the RCP operation during accidents.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2503-2508
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• 2013

Single-person households in the Seoul Metropolitan Area have increased sharply during recent 20-30 years. Despite of decreasing in the total population, the number of single-person household is predicted to increase continuously. However, the effect of single-person household growth on the domestic transport sector has not been studied concretely. In this study, the differences on trip generation characteristics by household size and attributes were figured out by analyzing Seoul Metropolitan Area Household Travel Behavior Survey (SMA-HTBS). Firstly, trip generation rates (trips/day/person) were produced by household attribute, household member attribute and trip attribute based on SMA-HTBS. Secondly, trip generation rate of single-person household and that of multi-person (2 or more) household were compared by significance test. It was found that trips generation characteristics of single-person household is quite different from those of multi-person household by housing type, residential type, living area, and transport mode. The result of this paper is expected to contribute developing more sophisticated trip generation model and transport policy reflecting trip generation characteristics of single-person household.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.187-190
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• 2006

In the present study, effects of tree-stream turbulence and surface trip wire on the flow past a sphere at $Re\;=\;0.4\;{\times}\;10^5\;{\sim}\;2.8\;{\times}\;10^5$ are investigated through wind tunnel experiments. Various types of grids are installed upstream of the sphere in order to change the tree-stream turbulence intensity. In the case of surface trip wire, 0.5mm and 2mm trip wires are attached from $20^{\circ}\;{\sim}\;90^{\circ}$ at $10^{\circ}$ interval along the streamwise direction. To investigate the flow around a sphere, drag measurement using a load cell, surface-pressure measurement, surface visualization using oil-flow pattern and near-wall velocity measurement using an I-type hot-wire probe are conducted. In the variation of free-stream turbulence, the critical Reynolds number decreases and drag crisis occurs earlier with increasing turbulence intensity. With increasing Reynolds number, the laminar separation point moves downstream, but the reattachment point after laminar separation and the main separation point are fixed, resulting in constant drag coefficient at each free-stream turbulence intensity. At the supercritical regime, as Reynolds number is further increased, the separation bubble is regressed but the reattachment and the main separation points are fixed. In the case of surface trip wire directly disturbing the boundary layer flow, the critical Reynolds number decreases further with trip wire located more downstream. However, the drag coefficient after drag crisis remains constant irrespective of the trip location.

• Journal of Korean Society of Transportation
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• v.29 no.2
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• pp.81-89
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• 2011

Trip distribution is the second step of the conventional travel demand estimation process, which connects trips between origin and destination, while transport mode choice is the third step of the process, which chooses transport mode among several modes serving for each origin-destination pair. Although these two steps have closely connected, they have been estimated independently each other in the estimation procedure. This paper presents an integrated model combining trip distribution and transport mode choice, and also presents its solution algorithm. The model integrates gravity model adopted for the trip distribution process with logit model employed for the mode choice process. The model would be expected to cope with the inconsistency issue existing in the conventional travel demand estimation procedure. This paper also presents an equilibrium condition, sensitivity of the model, and compares them with those of existing models.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.91-100
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• 2010

To understand the trip patterns of subway passengers is very important to making plans for an efficient subway system. Accordingly, there have been studies on mining and classifying useful patterns from large smart card transaction databases of the Metropolitan Seoul subway system. In this paper, we define a new classification of subway trip patterns and devise a classification algorithm for eleven trip patterns of the subway users from smart card transaction databases which have been produced about ten million transactions daily. We have implemented the algorithm and then applied it to one-day transaction database to classify the trip patterns of subway passengers. We have focused on the analysis of significant patterns such as round-trip patterns, commuter patterns, and unexpected interesting patterns. The distribution of the number of passengers in each trip pattern is plotted by the get-on time and get-off time of subway transactions, which illustrates the characteristics of the significant patterns.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.481-488
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• 2015

The recent trend in transportation planning information is to reduce traffic survey costs and enhance accuracy by using and converging various sources of external data. In Korea, mobile phone data can help generate useful transportation planning information, thanks to the universal use of mobile phones, which are present in a number greater than that of the population. This paper addresses measures to derive trip generation information from mobile phone data and verifies the value of the system for practical use by correlation analysis with KTDB trip generation data. The results show that trip generation information produced by mobile phone data correlates with existing (KTDB) trip generation data.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.93-100
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• 2010

Trip generation is the first step in the conventional four-step model and has great effects on overall demand forecasting, so accuracy really matters at this stage. A linear regression model is widely used as a current trip generation model for such plans as urban transportation and SOC facilities, assuming that the relationship between each socio-economic index and trip generation stays linear. But when rapid urban development or an urban planning structure has changed, socio-economic index data for trip estimation may be lacking to bring many errors in estimated trip. Hence, instead of assuming that a socio-economic index widely used for a general purpose, this study aims to develop a new trip generation model by type based on the market separation for the variables to reflect the characteristics of various zones. The study considered the various characteristics (land use, socio-economic) of zones to enhance the forecasting accuracy of a trip generation model, the first-step in forecasting transportation demands. For a market separation methodology to improve forecasting accuracy, data mining (CART) on the basis of trip generation was used along with a regression analysis. Findings of the study indicated as follows : First, the analysis of zone characteristics using the CART analysis showed that trip production was under the influence of socio-economic factors (men-women relative proportion, age group (22 to 29)), while trip attraction was affected by land use factors (the relative proportion of business facilities) and the socio-economic factor (the relative proportion of third industry workers). Second, model development by type showed as a result that trip generation coefficients revealed 0.977 to 0.987 (trip/person) for "production" 0.692 to 3.256 (trip/person) for "attraction", which brought the necessity for type classifications. Third, a measured verification was conducted, where "production" and "attraction" showed a higher suitability than the existing model. The trip generation model by type developed in this study, therefore, turned out to be superior to the existing one.

• Journal of Korean Society of Transportation
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• v.12 no.1
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• pp.43-54
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• 1994

The major concern of this paper is to investigate the properties of a stochastic equilibrium for each model system in terms of a consumer welfare measure. The primary assumption for this study is that a trip-maker would choose the trip from his origin zone which maximizes his personal welfare. This assumption, finally, leads to a singly constrained gravity model. The consumer welfare measure is derived from the concept of expected welfare of randomly sampled trip-makers. Each of the four different models considered in this paper is differentiated depending on the complexity of its model or the definition of its travel function. In this study, three different regions are chosen for the purpose of taking into account the effects of different zone-systems on the properties of a stochastic equilibrium : (i) Archerville region (5 zone) ; (ii) San Francisco Bay regions (30 zones) ; (iii) Houston, TX region (199 zones). It is concluded that almost identical, "global" consumer welfare values can be obtained in some cases of the gravity-type trip distribution models based on a stochastic equilibrium.