• Corrosion Science and Technology
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• v.10 no.4
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• pp.131-135
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• 2011

The demands of high-strength steel have been steadily increased to reduce the weight of vehicles. Although the TRIP steel has been the promising candidate material for the purpose, high strength hinders the application due to the susceptibility to hydrogen delayed fracture in the corrosive environment. Moreover, the testing method was not specified in the ISO standards. In this work, the test method to evaluate the susceptibility of hydrogen delayed fracture was studied by slow strain rate testing technique. The four test experimental parameters were studied : strain rate, hydrogen charging time, holding time after hydrogen charging, and holding time after cadmium plating. The steel was fractured by hydrogen in case the strain rate was in the range of $1{\times}10^{-4}{\sim}5{\times}10^{-7}/sec$. It was confirmed that the slow strain rate test is effective method to evaluate the susceptibility to hydrogen delayed fracture. The holding time over 24 hrs after hydrogen charging, nullified the hydrogen effect, that is, the specimen was no more susceptible to hydrogen after 24 hrs even though the specimen was fully hydrogen-charged. Moreover, cadmium electroplating could not prevent from diffusing out the hydrogen from the steel in the experiment. The effective experimental procedures were discussed.

• Journal of Gifted/Talented Education
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• v.23 no.6
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• pp.881-898
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• 2013

The purpose of this study was to compare the difference of semantic network about sedimentary environment between science gifted students and non-gifted students through field trip. The fifteen high school science gifted students and non-gifted students were participated in the field trip for this study. The geological field trip was performed in Chaseokgang, which suitable learning place for sedimentary environments. Data included field trip observation and students' inquiry activity reports. The inquiry activity reports were analyzed using the semantic network analysis method. The results of this study were as follows: First, the semantic network of science gifted students was larger and complex structures than that of the non-gifted students. Second, science gifted students were interpreted that changes of sedimentary environment was connected with the sorting and the roundness. On the other hand, semantic network of non-gifted students were become fragmented because they were not interpreted sedimentary environment related to scientific concepts.

• Journal of Korean Elementary Science Education
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• v.38 no.3
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• pp.345-359
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• 2019

The purpose of this study is to analyze the educational effects and the improvements of the 'Science Field Trips' Program which developed with the aim of fostering the prospective elementary school teachers' ability to manage science field trips. The participants were 13 senior students from a national university of education. The results of the study are as follows: First, with regard to the effectiveness in the science instruction aspect of the prospective teachers' geological field trip as an experiential activity, the responses of the participants were children's 'scientific knowledge'(69.2%), 'science related attitudes'(46.2%), and 'science inquiry'(30.8%). Second, regarding the effectiveness of the geological field trip in their management of science field trips aspects in the future, the responses of the participants were 'teaching strategies'(92.3%), 'plan implementation'(76.9%), 'teacher's science knowledge'(61.5%), 'self-confidence'(38.5%), 'enhancement of awareness of field trips'(23.1%), and 'career guidance'(7.7%). Third, with regard to the effectiveness in the science instruction aspect of their activities of planning a science field trip in their future working districts, the responses of the participants were children's 'science knowledge'(38.5%), 'science-related attitudes'(38.5%), and 'science inquiry'(23.1%). Fourth, regarding the effectiveness in their management of science field trips aspects of the activities of planning a science field trip, the responses of the participants were 'plan implementation'(92.3%), 'the identification of science field trip sites'(84.6%), 'teaching strategies'(76.9%), 'administrative affairs'(69.2%), 'teacher's science knowledge'(30.8%), 'enhancement of awareness of field trips'(23.1%), 'career guidance'(15.4%), and 'self-confidence' (15.4%). The improvements plans of the program and the suggestions for future research is also described in this study.

• Journal of the Korean Society of Earth Science Education
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• v.13 no.1
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• pp.1-14
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• 2020

The goal of this study is to develop a hands-on type polar field trip program to inform the importance of the recent polar research and to contribute to the spread of polar science culture. For this purpose, the direction of program development and field trip course were established based on the current Korea Polar Research Institute tour program and research exhibition facilities analysis. Based on this, a total of 6 types field trip programs were developed, including one basic tour program and one optional experience program for the overall introduction of polar research institutes and polar science fields, and four optional experience programs for each education participant that enables field trips and professional experiential learning activities by polar science field. The developed program was revised and supplemented through a total of two trials, and a field trip program manual was produced, including guidance scripts, experience kits, activity sites, and instructor guides for each field trip. At the end, a follow-up study was proposed based on the significance and research results of the developed program.

• Journal of the Korean earth science society
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• v.38 no.4
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• pp.303-320
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• 2017

Purpose of this study is understanding of group modeling process focusing on constraints with geological field trip applied on social-construction of scientific model. This study was carried out on 12 students of 3 groups who participate in the study 'S' gifted education center. Students were conducted to theme of 'How was formation of Mt. Gwanak?' on 2 field trip classes and 3 modeling classes. Semi-structured interviews, all discourse of field trip and modeling classes, records of personal and group activity were analyzed to constraints based on theoretical background proposed by Nersessian (2008). Results as follows. First, sources of constraints are scientific knowledge, contents observed by students during field trips and additional materials things to be explained by model during modeling class with geological field trip applied on social-construction of scientific model. Second, there are 3 types of constraints to affect making group modeling. It is that shared constraint which used commonly by all the group members. It called selected constraint that used during the initial modeling and later were reflected on for use in the group modeling. And it is that generated constraints, which were not in the initial modeling but were used later in the group modeling. This study suggests that not only the constraints can help to understand of making group model through how they used but also show that example of learning with geological field trip on social-construction of scientific model to contribute school science.

• Journal of the Korean earth science society
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• v.28 no.6
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• pp.686-698
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• 2007

The purpose of this study was to investigate the perceptions and practices of secondary science teachers who participated in an Earth science teachers' research roup about teaching geologic field trips. Four Earth science teachers participated in this study. Data included field trip observations, semi-structured interviews with teachers and students, and analysis of instructional materials and students' reports from the field trip. Field trip observations and interviews were video- and audio-taped and transcribed. Results indicated that teacher participants focused more on aesthetic objectives for geologic field trip. The participants' instruction tended to show rather teacher-centered explanation due to limited time at each field site though various teaching strategies were used at times to engage students in a scientific inquiry. This group of teachers strived to develop their professional ability to guide geologic field trip by working with a small study group with colleagues, participating geologic field trips, and enrolling graduate programs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.7-15
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• 2011

The travel time value is important factor for the evaluation of feasibility the transportation facility investment. The existing method for calculation of the travel time for each mode uses daily average trip purpose. So the value of travel time is constant because it is estimated with only daily average proportion. This daily constant time value can distort the results of future demands of toll roads or economic appraisals for the projects. The proportion of the trip purpose varies by time periods. Accordingly the value of travel time also varies by time periods. In this study, times periods are classified as morning peak, evening peak, business time off-peak, and non-business time off-peak. And trip purpose proportions are sorted by each time period from raw data of Seoul household trip study, then the value of travel time for each time period is estimated with these sorted purpose proportions. A case study of Seoul Jung-gu and Yongsan-gu performed with newly estimated time value by time periods. The result of benefit calculation with the daily constant time value is overestimated approximately annual 2.5 billion Won compared by time values by time periods. The demands of toll roads are also overestimated with the existing daily constant time value by daily 3,500 vehicles and total revenue of toll roads are overestimated by annually 1 billion Won. In conclusion, the value of travel time by each time period enables the more precise economic evaluation of the transportation facility investment projects, mode choice behavior, and route choice behavior especially for toll roads.

• Journal of Korean Society of Transportation
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• v.24 no.7 s.93
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• pp.53-62
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• 2006

The aim of this paper is to analyze the changes in the travel pattern of public transit users, service satisfaction before and after public transportation system reform in Daegu. For this purpose, we conducted a survey of people on public transit users and the results of study are as follows : First, it was found that transfer trip had increased, especially concerning the changes of travel pattern from bus trip to the transfer trip between the bus and subway. Because it makes a financial sense to transfer based on free charge transfer system. Secondly, the transfer satisfaction was improved for public transit users, but they are still reluctant to use transfer system.

• Journal of the Korean Dietetic Association
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• v.5 no.2
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• pp.182-193
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• 1999

The purpose of this research is to analysis the general job of 76 dietitian on common management of school food service in Kyoung-buk area. In this research we asked them some general aspects, and made use of three variants(job performing time, the degree of major recognition, and the degree of difficulty) each question after classifying their jobs into 13 standard jobs. Statistical data analysis was completed using SPSS package program. The results of this survey showed the following : 1. The types of common management are as in the following : of the whole 76, 37 on the rotative trip to one single school, 8 to two schools, 1 to three schools, 28 on the trip to one single school plus central food production and 1 on the trip to two schools plus central food production. 2. The average job performing time in his or her school is 2813 minutes(8.52 hours) per week. 3. The factor of the evaluation and study of school foodservice has the highest level in every variant, but there were no standard job which needed the high-level difficulty and the longer job performing time as it needed the low degree of major recognition.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.107-118
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• 2012

The purpose of the study is to analyze the travel characteristics of freight trucks in metropolitan areas, focusing on activity generation, destination choice, and trip chaining behaviors. The results showed that the number of service companies at departure areas has a primary influence on the activity generation pattern and destination choice behavior of trucks in metropolitan areas. The number of trips within a trip chain is largest, in case where the prevailing industry in destination areas is wholesale or retail and the shipment item is food or beverage. These results imply that for the reasonable estimation of truck travel demand both the trip chaining behaviors and the industrial compositions in departure and destination areas should be separately considered for each type of commodity.