• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.263-266
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• 2009

Transformation induced plasticity (TRIP) steel consisting of ferrite, austenite, and bainite phases was regarded as an excellent candidate for automotive applications due to the good combination of ductility and strength. The aim of the present study was to understand the microstructural characteristics of ultrafine grained (UFG) TRIP low-carbon steel fabricated via equal channel angular pressing accompanied with intercritical- and isothermal-annealing treatments. When compared to coarse grained counterpart, only the volume fraction of austenite phase in UFG TRIP steel remained unchanged, but all other microstructural variables such as size and morphology were different. It was found that UFG TRIP steel showed the homogeneous distribution of each constituent phase, which was discussed in terms of annealing treatments done in this study.

• Journal of the Economic Geographical Society of Korea
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• v.10 no.1
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• pp.44-63
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• 2007

The purpose of this study is to propose mining processes in the large trip-transaction database of the Metropolitan Seoul area and to analyze the spatial characteristics of travel behavior. For the purpose. this study introduces a mining algorithm developed for exploring trip patterns from the large trip-transaction database produced every day by transit users in the Metropolitan Seoul area. The algorithm computes trip chains of transit users by using the bus routes and a graph of the subway stops in the Seoul subway network. We explore the transfer frequency of the transit users in their trip chains in a day transaction database of three different years. We find the number of transit users who transfer to other bus or subway is increasing yearly. From the trip chains of the large trip-transaction database, trip patterns are mined to analyze how transit users travel in the public transportation system. The mining algorithm is a kind of level-wise approaches to find frequent trip patterns. The resulting frequent patterns are illustrated to show top-ranked subway stations and bus stops in their supports. From the outputs, we explore the travel patterns of three different time zones in a day. We obtain sufficient differences in the spatial structures in the travel patterns of origin and destination depending on time zones. In order to examine the changes in the travel patterns along time, we apply the algorithm to one day data per year since 2004. The results are visualized by utilizing GIS, and then the spatial characteristics of travel patterns are analyzed. The spatial distribution of trip origins and destinations shows the sharp distinction among time zones.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.657-662
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• 2011

The relationship between household attributes and trip generation can only be found in Seoul Metropolitan Household Travel Survey, which has been implemented every 5 years. However, various household attributes' impact on trip generation has not been analyzed closely. This paper compared and analyzed those impact. The results could be useful when trip generation models are studied in the future. They are as follows. The household size should be an important classification criteria when household trip generation is estimated. The traditional assumption that the relationship between household auto ownership and trip generation is positive and linear correlation should be reconsidered. Weekday travel data only did not showed that housing type has an influence on trip generation. Household income is unrelated with trip generation among single-person household, while multi-person household is related strongly. However, when trips are classified by purpose, impact of household income on trip generation are varied by trip purpose. Especially, the increase in single-person household can not be overlooked when trip generation is forecasted.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1532-1537
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• 2009

Nowadays the diversity and large-capacity of electric appliances are strong effect on electrical fires augment in an alarming way. But, as the inactive response characteristics of the existing RCD (Residual Current protective Device) used on low voltage power distribution lines, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore this paper is confirmed the unreliability of the existing RCD by electrical faults simulation and is proposed a auxiliary trip device of RCD by using a high precision current sensor (namely, reed switch) for the prevention of electrical disasters in low voltage power distribution lines caused by overload or electric short circuit faults. The sensitive reed switch in the proposed ATD (auxiliary trip device) exactly detects the increased magnetic flux with the overload or the short current caused by a number of electrical faults, and then rapidly cuts off the existing RCD. The proposed auxiliary trip device of RCD is confirmed the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker through various operation performance analysis. The proposed ATD can also prevent electrical disaster, like as electrical fires, which resulted from the malfunction and inactive response characteristics of the existing RCD.

• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.7-19
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• 2011

Using 2006 metropolitan household travel survey data, this study analyzes trip behaviors based on a concept of trip chains using both trip purpose and number of trip linkages. For the analysis, trip chains are classified into two groups depending on including commute trips. Each group is further classified into a single linkage (i.e., Origin-Destination trips without any intermediate stop-by) and multiple linkages (Origin-Destination trip with at least one intermediate stop-by). The analysis is conducted using the two-step Nested Logit Model. Computational results identifying the characteristics of single and multiple linkages show that the young, male and office employee drivers tend to have more multiple linkages than single linkages in their trips. In contrast, it is shown that a driver whose monthly income is less than 3,000,000 Korean Won with a longer commute time more likely to make a trip chain with single linkages (p<0.0001).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.6
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• pp.124-140
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• 2023

The rapid growth in shared E-scooters worldwide has led to many studies on the topic. The results of these studies are still in the early stages, and the main factors affecting trips are being identified. In particular, the development of trip-generation models is very important for transportation planning, and a new transportation mode for developing the models for shared E-scooters is lacking both domestically and internationally. This study aims to develop a trip generation model for shared E-scooters using significant variables by thoroughly reviewing previous studies. The trip characteristics of major service areas and other areas may differ owing to the trip characteristics of the mode. The trip generation models were developed based on the service trip density by dividing the areas by service level. The factors affecting shared E-scooter trips in major service areas included the presence of universities, closeness centrality, and cultural areas, while factors affecting the trips in minor service areas included the presence of universities, betweenness centrality, and trip distance. The developed models provide basic information that can be used to establish transport policies for introducing shared E-scooters in cities in the future.

• Journal of The Geomorphological Association of Korea
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• v.19 no.2
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• pp.17-29
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• 2012

In order to improve a trip pattern in Mt. Halla climbing only to a summit, two trip programs with nature interpretation have been developed using the geomorphic characteristics of Mt. Halla which are distinct from those of mountains in the Korean peninsula. It also aims to help conservation of natural environment of Mt. Halla and to enhance the visitor satisfaction in Mt. Halla. The subalpine trip program is carried out on a 1.5 km-long trail between Wissaeoreum Hut and Janggumokoreum. Program participants are able to learn expertise about, and understand vulnerability of, a subalpine ecosystem, Consequently, the program can obtain an educational attainment getting them to recognize the necessity of preserving the subalpine zone of Mt. Halla as an important natural resource. The mountain river trip program is performed on a 1.5 km-long reach of Byeongmun River between Gwaneumsa trailhead and a gorge upstream of Gurin Cave. The program is capable of exhibiting effectively the river characteristics of Jeju Island using the geomorphic and hydrologic properties of Byeongmun River which differ from those of rivers in the Korean peninsula. Since the subalpine grassland and ephemeral stream of Mt. Halla are the visiting places which are rarely experienced in the Korean peninsula, the program participants can understand the regionality of Jeju Island as well as Mt. Halla through trip activities.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.1
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• pp.55-70
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• 2018

Recently, as shared transportation services has expanded, integrated mobility services that link personal transportation and public transportation are paid attention. To do this, it is necessary to analyze trip mode chaining behavior. This study analyzed the characteristics of the trip mode chaining behavior using the 2010 travel diary survey in Seoul, and analyzed factors to affect mode choice of trip chaining through the multinomial logit model. The transportation means were classified into passenger cars, city buses, intercity buses, railways, taxis, and others, and 25 trip mode chaining types were identified. Among them, the trip share connected between city bus and railways was the highest. It was also found that the trip mode chaining occurred mainly at commuting and in the morning and afternoon peak. According to the model results, the mode choice of trip chaining is significantly influenced by individual attributes (sex and age), household attributes (car ownership and income), trip attributes (trip purpose, trip time and trip length), and arrival area attributes (number of subway lines and bus lines, ratio of commercial area, land use mix and central region).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.6
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• pp.126-139
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• 2011

In the traditional four-step travel demand models, each step is sequentially conducted following the model estimation at the previous step. The accuracy of the following model is partly dependent on whether the model at the former stage was properly established or not. Therefore, trip generation, which is the first step in this conventional model, has great effects on the modeling process and forecasting results. Linear regression models for trip generation of Seoul Metropolitan Area might increase the forcasting errors, since a variety of land-use characteristics are not considered. Hence, in this study, zonal factors such as socioeconomic and land use variables are included to improve the elaboration of trip generation. Comparing the %RMSE with the existing models, which contain bigger errors in the zones highly based on the secondary and tertiary industries than residence-based, the trip generation models including those variables seem more appropriate overall.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2005.06a
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• pp.57-60
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• 2005