• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.768-773
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• 2019

The Fenton reaction, which evaluates the electrochemical durability of polymer membranes of polymer electrolyte fuel cells (PEMFC), and the degradation of polymer membranes by OCV holding method are compared. The Fenton reaction is a method that can evaluate the chemical durability of the polymer membrane at outside the cell in a shorter time than the OCV Holding method. The Fenton reaction was carried out at 30% hydrogen peroxide, 10 ppm iron, and $80^{\circ}C$ for 24 hours. OCV Holding was driven at $90^{\circ}C$, 30% relative humidity and OCV for 168 hours. The Fenton reaction caused a lot of degradation inside the polymer membrane. On the other hand, in OCV Holding, the membrane thickness was thinned by the entire surface and internal degradation. The fluorine emission rate was more than 10 times higher than that of OCV Holding due to the Fenton reaction. The hydrogen permeation rate increased about 30% at 24 hours of Fenton reaction. At OCV Holding, hydrogen permeability decreased after 24 hours and then increased. As a whole, there was a difference in a membranes deteriorated by Fenton reaction and OCV Holding.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.5
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• pp.421-429
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• 2021

The purpose of this study was to identify the change in the girth of anthropometric variables during menstrual cycle, and to provide basal data for health promotion program development during pre-menstrual phase and menstrual phase. Participants were 10 healthy women university students without menstrual irregularity, subjective premenstrual syndrome, premenstrual dysphoric disorder, dymenorrhea, obstetrician and gynecologic disease. Chest girth(axillary and papillary), waist girth(half point between iliac crest and 12th rib, and navel), and hip girth were repeatedly measured in menstrual phase, follicular phase, luteal phase during single menstrual cycle. As a result, axillary chest girth in menstrual phase was significantly increased than that in luteal phase. Papillary chest girth and waist girth at half point between iliac crest and 12th rib in menstrual phase were significantly increased than those in follicular phase. No significance was shown in chest and waist girth between follicular and luteal phase. No significance was shown in hip girth during menstrual cycle. In conclusion, signicant difference was shown in chest and waist girth during menstrual cycle. And it is suggested that succeeding research should be carried out with reference to body weight, body fat, blood and local hormone concentration during menstrual cycle.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.684-689
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• 2021

In this paper, we develop a cost effective and disposable voltammetric sensing platform involving screen-printed carbon electrode (SPCE) modified with the nanocomposites composed of multi-walled carbon nanotubes, polyelectrolyte, and tyrosinase for bisphenol A. This is known as an endocrine disruptor which is also related to chronic diseases such as obesity, diabetes, cardiovascular and female reproductive diseases, precocious puberty, and infertility. A negatively charged oxidized multi-walled carbon nanotubes (MWCNTs) wrapped with a positively charged polyelectrolyte, e.g., polydiallyldimethylammonium, was first wrapped with a negatively charged tyrosinae layer via electrostatic interaction and assembled onto oxygen plasma treated SPCE. The nanocomposite modified SPCE was then immersed into different concentrations of bisphenol A for a given time where the tyrosinase reacted with OH group in the bisphenol A to produce the product, 4,4'-isopropylidenebis(1,2-benzoquinone). Cyclic and differential pulse voltammetries at the potential of -0.08 V vs. Ag/AgCl was employed and peak current changes responsible to the reduction of 4,4'-isopropylidenebis(1,2-benzoquinone) were measured which linearly increased with respect to the bisphenol A concentration. In addition, the SPCE based sensor showed excellent selectivity toward an interferent agent, bisphenol S, which has a very similar structure. Finally, the sensor was applied to the analysis of bisphenol A present in an environmental sample solution prepared in our laboratory.

• Journal of the Korean Institute of Gas
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• v.25 no.5
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• pp.11-18
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• 2021

Since hydrogen has the lower minimum ignition energy than that of gasoline, hydrogen could be also appropriate for the IC engine systems. However, due to the low ignition energy, there might be a 'back-fire' and 'pre-ignition' problems with hydrogen SI(Spark-ignition) combustion. In this research, cooling effects of intake gas mixture on the improvement of the maximum power output were evaluated in a 2.4 L SI engine. There were two ways to cool intake gas mixtures. The first one was cooling intake fresh air by adjusting inter-cooler system after turbocharger. The other one was cooling hydrogen fuel before supplying by using heat ex-changer. Cooling hydrogen was performed under natural aspired condition. The result showed that cooling fresh air from 40 ℃ to 20~30 ℃ improved the maximum brake power up to 6.5~8.6 % and cooling hydrogen fuel as -6 ℃ enhanced the maximum brake power likewise.

• Journal of the Korean Applied Science and Technology
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• v.38 no.5
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• pp.1241-1248
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• 2021

In order to figure out various environmental problems, various governments and companies are investigating more environmentally policies and technologies. In other words, activated carbon is widely used for the adsorption of different harmful gases and waste liquid treatment. However since the required surface properties are different in various industry, depending on the adsorption properties, the development of activated carbon demand in different ways. In this work, we have investigated and developed the activated carbon surface to improve the hydrophilic properties by nitric acid treatment through reforming of activated carbon.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.2
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• pp.146-158
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• 2021

We are to introduce an example of ESD in connection with SDGs through liberal arts courses opened at the College of Education. We analyzed the awareness of the carbon footprint expressed by 42 preservice teachers in a class designed in connection with SDGs 13 goal, 'climate action'. The pre-service teachers wrote a carbon diet diary, a checklist for the level of practice that emits carbon in daily life, and freely expressed the source and proportion of their carbon emissions through the carbon footprint drawing activity. In items of electricity use, public transportation use, and garbage disposal, the level of practice was positive, but water use was analyzed in a negative way. The pre-service teachers who expressed the carbon footprint in 2-3 items reached a majority, showing limitations in recognizing the carbon emission situation in their daily life. Pre-service teachers will be the main actors of education on the environmental issues of the earth at the school site, and the carbon literacy of pre-service teachers will directly or indirectly affect students. We hope that various ESD programs linked to the 17 SDGs will be developed and applied to the educational field to contribute to sustainable global environmental education.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.2
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• pp.202-211
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• 2021

The purpose of this study is to find out the Learning elements in 'Curriculum Reconstruction' of Elementary Pre-service Teachers in Connection with 'The weather and our daily life'. The pre-service teachers who participated in the study formed a research group of 29 students in 2nd grade who are attending the first semester of A university of education and taking courses in 'teaching research 1'. Participants described the learning topics and contents they would like to add to curriculum 'The weather and our daily life'. Each response was analyzed and classified based on scientific terms related to weather or climate. The results of the study were as follows. First, there were three learning topics related to weather, such as water phenomena in the atmosphere, fine dust and yellow dust phenomena, and light or electricity phenomena, and two topics related to climate such as abnormal climate and global warming. Second, interest in the problem of fine dust and yellow dust in the atmosphere was relatively high. Third, the interest in learning in the knowledge area was relatively higher than in the learning in the function or attitude area. Through these research results, it can be confirmed that it is necessary to develop a climate change or climate crisis education program.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.664-670
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• 2021

Stainless steel was applied as bipolar plate (BP) of polymer electrolyte membrane fuel cell (PEMFC) due to high mechanical strength, electrical conductivity, and good machinability. However, stainless steel was corroded and increased contact resistance resulting PEMFC performance decrease. Although the corrosion resistance could be improved by surface treatment such as noble metal coating, there is a disadvantage of cost increase. The stainless steel corrosion behavior and passive layer influence on PEMFC performance should be studied to improve durability and economics of metal bipolar plate. In this study, SUS316L bipolar plate of 25 cm² active area was manufactured, and experiments were conducted for corrosion behavior at an anode and cathode. The influence of SUS316L BP corrosion on fuel cell performance was measured using the polarization curve, impedance, and contact resistance. The metal ion concentration in drained water was analyzed during fuel cell operation with SUS316L BP. It was confirmed that the corrosion occurs more severely at the anode than at the cathode for SUS316L BP. The contact resistance was increased due to the passivation of SUS316L during fuel cell operation, and metal ions continuously dissolved even after the passive layer formation.

• Journal of Digital Convergence
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• v.19 no.9
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• pp.169-180
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• 2021

This study analyzed research trends on smart logistics in Korea by conducting social network analysis (SNA) using R. The purpose of this study is to enhance the understanding of the smart logistics field along with the smart logistics status and policy review, and to suggest implications and future research tasks. The analysis period and subjects were 128 academic journal papers on smart logistics-related topics over the past 10 years (2011-2020), and the results were divided into the first half (2011-2015) and the second half (2016-2020). The analysis of the study was carried out step-by-step through frequency analysis, network centrality analysis, and visualization. As a result of the study, the quantitative increase and diversification of the research field were confirmed. It was also confirmed that the concentration of research on core areas increased by increasing the proportion of duplicate keywords. In addition, keywords with high betweenness centrality and degree centrality score such as Logistics, Authentication, Smart, Service, RFID, Technology, and Revolution were presented. Lastly, this study reviewed the structure with a focus on betweenness centrality after visualizing the network with main keywords. As a result, early research was focused on the field of logistics, and after 2016, it was confirmed that the center of research was diversifying and expanding with the development of the 4^th industrial revolution and major technologies.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1013-1027
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• 2021

Images taken with KOMPSAT-3 have additional NIR and PAN bands, as well as RGB regions of the visible ray band, compared to imagestaken with a standard camera. Furthermore, electrical and optical properties must be considered because a wide radius area of approximately 17 km or more is photographed at an altitude of 685 km above the ground. In other words, the camera sensor of KOMPSAT-3 is distorted by each CCD pixel, characteristics of each band,sensitivity and time-dependent change, CCD geometry. In order to solve the distortion, correction of the sensors is essential. In this paper, we propose a method for detecting uniform regions in side-slider-based KOMPSAT-3 images using segment-based noise analysis. After detecting a uniform area with the corresponding algorithm, a correction table was created for each sensor to apply the non-uniformity correction algorithm, and satellite image correction was performed using the created correction table. As a result, the proposed method reduced the distortion of the satellite image,such as vertical noise, compared to the conventional method. The relative radiation accuracy index, which is an index based on mean square error (RA) and an index based on absolute error (RE), wasfound to have a comparative advantage of 0.3 percent and 0.15 percent, respectively, over the conventional method.