• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1125-1131
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• 2016

The purpose of this paper is to establish an evaluation criteria for pavement condition in bicycle road. The suggested criteria would help in the activation policy of bicycle use. The conventional evaluation criteria is difficult to be applied for the bicycle road since the bicycle road is sensitive to changes in the driving environments such as obstacles and bumps. This study presents the evaluation criteria that is suitable for bicycle road. The criteria was suggested in 5 grades through the impact acceleration range of RMSI (Road Monitoring System using ICT). The grades of the criteria are divided into a range of grade A to E. The grade A is a very good condition, while the grade E is a state that requires immediate maintenance. This study were confirmed the validity through the survey of user's satisfaction. According to the results of survey, the grade A was shown correlation of 91%. The grade E requiring immediate repair was presented correlation of 94%. It showed that the results of surveying the bicycle road users are highly correlated with the suggested criteria for pavement condition. It showed that the criteria are highly correlated with the survey results. Suggested criteria using the RMSI is expected to be effective for maintenance of the bicycle road. In addition, it is expected to ensure the serviceability and safety for the bicycle users.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.142-147
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• 2009

The influence of graphitization of carbon support on the electrochemical corrosion of carbon and sintering of Pt particles are investigated by measuring $CO_2$ emission at a constant potential of 1.4 V for 30 min using on-line mass spectrometry and cyclic voltammogram. In comparison to commercial Pt/C (from Johnson Matthey), highly graphitized carbon nanofiber (CNF) supported Pt catalyst exhibits lower performance degradation and $CO_2$ emission. As the more carbon corrosion occurred, the more prominent changes were detected in electrochemical characteristics of fuel cell. This indicates that the carbon corrosion affects significantly the fuel cell durability. From the observed results, CNF is considered to be more corrosion resistant material as a catalyst support. However, CNF shows higher aggregation of Pt particles under repeated cyclic voltammetry between 0 and 0.8 V where the carbon corrosion is not initiated.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.81-88
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• 2010

Small size polymer electrolyte membrane fuel cell (PEMFC) stacks were prepared using carbon composite and graphite bipolar plates and their performances were evaluated on reactant gas and operating time. In comparison to single cell and stack, it was identified that home-made bipolar plate was well-designed to maximize stack performance as high as that of single cell. During long-term operation, the performances of stacks using two different kinds of bipolar plates were compared. The decrease of performance in both stacks was accelerated with increasing load current. It was observed from stack test that the stack performance using carbon composite bipolar plate was very similar to that using graphite bipolar plate.

• Korean Journal of Environment and Ecology
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• v.25 no.5
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• pp.799-813
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• 2011

Increasing mountain biking (MTB) in forest recreation areas is changing the behavioral patterns in the areas where hiking has been a dominant activity, and it may cause ecological and social impacts to the areas. This study examined hikers' perceived conflicts by MTB including the relationship between socio-demographic and visiting characteristics and perceived conflict. On-site survey was conducted in Mudeungsan Provincial Park (MPP), Korea, during September, 2010. Out of 388 hikers participated in the survey, 374 responses were used for data analysis. 30.2% of the respondents encountered or saw MTB (avg.: 1.7 times) in MPP. Overall, 77.1% of respondents thought MTB in MPP was a problem. 73.5%~83.2% of respondents perceived conflict by four major MTB behaviors (e.g., too fast running MTB in trails; MTB bikes occupying trails; MTB bikes passing by hikers too closely; MTB bikers doing unpleasant behaviors to hikers). Based on the type of conflict, 48.5~62.4% of respondents fell in the type of "social values conflict (SVC)", 11.1~32.4%, "interpersonal conflict (IC)", and 16.8~26.6%, "no conflict (NC)", respectively. Types of conflicts were related with sociodemographic (e.g., gender, age, education) and visiting characteristics (e.g., number of visits, experience of encountering MTB). Such relationships were nonexistent in most cases when the "experience of encountering MTB" was controlled.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.14-25
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• 2021

With the spread of COVID-19 and the government policy of social distancing, the demand for subways and buses is decreasing, whereas the demand for public bicycles and personal transportation is increasing. Hence, research is needed to understand the characteristics of this phenomenon and to prove the statistical reliability of the correlation between the subway and shared bicycle demands. In this study, the correlation between the number of confirmed COVID-19 cases and the replacement rate of subway and public bicycle demands was examined, but the statistical significance was not significant. However, during the period of September to December 2020, in which the number of confirmed COVID-19 cases in Seoul started to increase rapidly, there was a correlation between the number of confirmed COVID-19 cases and the replacement ratio. If the number of confirmed COVID-19 cases increases by more than a certain number, public bicycles are expected to play a significant role as alternates to the subways. It is expected that the role of public bicycles will increase, and that it is possible to suggest the direction of transportation operation and policy establishment for the continuation of COVID-19 countermeasures in field demonstration after elementary technology development. It is also expected that this study will suggest a direction for future development and policymaking.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.4
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• pp.115-124
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• 2022

Unlike the semi-public system of city buses, Seoul's townbus are operated on a private operating system, which is poor condition to the changes in the environment. Sales decreased due to a decrease in the number of passengers due to COVID-19 and a demand for conversion due to the advent of competitive transportation methods, and the financial support of Seoul Metropolitan Government is continuously increasing. In this study, to analyze the characteristics of townbus operated by a private operating system, the townbus sales and surplus companies were analyzed by what factors were affected. For the analysis data, townbus financial statements of Seoul in 2018 were used, and townbus sales and surplus companies were applied as dependent variables, and townbus operation system, satisfaction survey, humanities and social variables, and subway and public bicycle characteristics were applied as independent variables. As a result of the analysis, the sales is affected by operating hours per vehicle, in-vehicle safety, the number of households, the number of elderly people, and public bicycle variables, and surplus companies are affected by in-vehicle safety, reliability, and public bicycle variables. In particular, public bicycles, a competitive means of transportation, had an impact on industry sales, and the townbus business environment is expected to become more difficult as time goes by. The industry is seeking self-rescue measures, and Seoul is required to strengthen financial support so that townbus can operate stably.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.517-522
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• 2023

A chemical/mechanical durability test of polymer membrane evaluation method is used in which air and hydrogen are supplied to the proton exchange membrane fuel cell (PEMFC) and wet/dry is repeated in the open circuit voltage (OCV) state. In this protocol, when wet/dry is repeated, voltage increase/decrease is repeated, resulting in electrode degradation. When the membrane durability is excellent, the number of voltage changes increases and the evaluation is terminated due to electrode degradation, which may cause a problem that the original purpose of membrane durability evaluation cannot be performed. In this study, the same protocol as the department of energy (DOE) was used, but oxygen was used instead of air as the cathode gas, and the wet/dry time and flow rate were also increased to increase the chemical/mechanical degradation rate of the membrane, thereby shortening the durability evaluation time of the membrane to improve these problems. The durability test of the Nafion 211 membrane electrode assembly (MEA) was completed after 2,300 cycles by increasing the acceleration by 2.6 times using oxygen instead of air. This protocol also accelerated degradation of the membrane and accelerated degradation of the electrode catalyst, which also had the advantage of simultaneously evaluating the durability of the membrane and the electrode.

• Journal of The Korean Association For Science Education
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• v.37 no.1
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• pp.9-16
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• 2017

The result of TIMSS 2015 was announced at the end of 2016. In this research, we conducted test-curriculum matching analysis for 8th grade earth science and analyzed Korean students' percentage of correct answers and responses for TIMSS earth science test items. According to the results, Korean students showed high percentage of correct answers when the item topics are covered in the 2009 revised science curriculum, and Korean students revealed their weakness in constructed response items since the percentage for correct answers on constructed response items is half that of multiple choice items. Depending on the earth science topic, for 'solid earth' area, which includes earth's structure and physical features, as well as earth's processes and history, students showed high percentage of correct answers for multiple choice items. Students, however, showed low percentage of correct answers for items that require applying knowledge to everyday situations and connecting with other areas of science such as biology. For 'atmosphere and ocean' areas, which include earth's processes and cycles, students showed low percentage of scores for climate comparison between regions, features of global warming, etc. For the area of 'universe', students showed high percentage of scores for the earth's rotation and revolution, the moon's gravity, and so on because they have learned these topics since primary school. Discussed in the conclusion are ways to secure content connection between the primary and middle school earth science curriculums, ways to develop students' science-inquiry related competencies, and so on to improve middle school earth science curriculum as well as teaching and learning.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.210-218
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• 1990

The survival and transfer of chromosomal genes coding for the synthesis of amino acids (threonine, tryptophan, histidine, leucine, methionine) and of plasmid-borne genes coding for resistance to antibiotics (chloramphenicol, kanamycin, erythromycin) by transformation in sterile and nonsterile soil (the soil was amended to 12% vol/vol with the clay mineral, montmorillonite) was studied. In pure culture, the numbers of vegetative cells of the Bacillus subtilis strains decreased by 1 to 1.5 orders of magnitude within one week, but spores of each strain showed lesser decreases. In sterile soil, the populations of vegetative cells and spores decreased by 1.5 to 3 orders of magnitude within 2 to 4 days and then showed little additional decreased. The transformation frequencies (number of transformants/numbers of donors and recipients) of individual amino acid-genes invitro ranged from $1.3{\pm}0.6{\times}10^{-6}$ to $6.0{\pm}2.36{\times}10^{-6}$, of two amino acid-genes from $8.5{\pm}0.7{\times}10^{-8}$ to $3.1{\pm}0.6{\times}10^{-7}$, and of the antibiotic-resistance genes from $1.5{\pm} 0.2{\itmes} 10^{-7}$ to $1.4{\pm} 0.4{\times} 10^{-5}$ . In sterile soil, the frequencies of transfer of individual amino acid-genes ranged from $2.0{\times} 10^{-7}$ to $2.0{\times} 10^{-5}$ and of the antibiotic-resistance genes from $2.0{\times} 10^{-7}$ to $9.4{\pm} 4.7{\times} 10^{-6}$. The transfer of two amino acid-genes in sterile soil was detected at a frequency of $2.0{\times} 10^{-6}$ to $4.5{\times} 10^{-6}$, but only in three instances. The transformation frequencies of antibiotic-resistance genes in nonsterile soil were essentially similar to those in sterile soil. However, to detect transformants in nonsterile soil, higher concentrations of antibiotics were needed, as the result of the large numbers of indigenous soil bacteria resistant to the concentration of antibiotics used in the sterile soil and in vitro studies. The results of these studies show that genes can be transferred by transformation in soil and that this mechanism of transfer must be considered in risk assessment of the release of genetically engineered microorganisms to the environment.