• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.119-143
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• 2021

Selecting liquid methane as fuel is a prevailing trend for recent rocket engine developments around the world, triggered by its affordability, reusability, storability for deep space exploration, and prospect for in-situ resource utilization. Given years of time required for acquiring a new rocket engine, a national-level R&D program to develop a methane engine is highly desirable at the earliest opportunity in order to catch up with this worldwide trend towards reusing launch vehicles for competitiveness and mission flexibility. In light of the monumental cost associated with development, fabrication, and testing of a booster stage engine, it is strategically a prudent choice to start with a low-thrust engine and build up space application cases.

• Land and Housing Review
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• v.13 no.3
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• pp.21-38
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• 2022

In this study, the housing-related characteristics of the youth are reviewed using data from the 4^th - 14^th Youth Panel Survey(YP2007) of the Korea Employment Information Service in the period 2010 - 2020. The factors that affect the characteristics of their dwelling are analysed. As a result, males, highly educated, and employed people are more likely to live in their own homes and apartments, but many of them seem to be living with their parents. On the contrary, economically independent young people tend to occupy their dwellings in the form of jeonsei/monthly rent and live in multi-family units, villas, and officetel. To support the youth in overcoming their key issues such as housing affordability, jobs, and marriage, so that they can play their roles, the cost of homeownership and rent should be tailored to their economic situations.

• Fashion & Textile Research Journal
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• v.25 no.4
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• pp.419-428
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• 2023

This study examines customer reviews from online stores of Korean vegan fashion brands to determine the qualities that customers value in vegan fashion items. For this purpose, we conducted a case study of online reviews-2,285 reviews were collected and analyzed. The results are as follows: The clothing evaluation criteria for vegan fashion products can be divided into four categories: aesthetics, material characteristics, affordability, and characteristics. This suggests that evaluation standards for vegan fashion items operate at multiple levels. The animal welfare aspect of the product was the most important factor, followed closely by how well the clothes fit. High-quality vegan materials and the use of recycled materials that are environmentally friendly were emphasized. The findings of this study suggest that even for vegan products, stylistic features remain an essential component of fashion items. To understand the main aspects of clothing evaluation criteria in the current vegan fashion market, this study differs from other studies in that it examined online reviews of vegan fashion brands. This comprehensive analysis contributes to a deeper understanding of customer preferences and highlights the importance of ethical considerations alongside style in the evaluation of vegan fashion items, providing valuable insights for the industry. Moving forward, this study is significant in suggesting that vegan fashion brands should develop their products as well as their brands, capitalizing on the demand for ethically conscious and stylish options.

• Journal of Science Education
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• v.47 no.2
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• pp.154-166
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• 2023

It has been known that the tool characteristics embedded in physical tools and virtual tools act with different underlying mechanisms in a user's knowledge acquisition and conceptual understanding. This overview study examines the learning process through the use of physical and virtual tools from the perspective of conceptual frameworks, affordability that tools present, and the depth of cognitive engagement that occurs in the process of learning concepts through various learning activities. Based on the conceptual frameworks, the results of previous comparative studies were reinterpreted. It was found that what mattered for learning is the amount of new information that a tool provides and the different level of cognitive engagement that students use through various learning activities. Finally, the implications to be considered when teachers use physical and virtual tools to help students better understand various concepts are discussed.

• Journal of Sensor Science and Technology
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• v.32 no.3
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• pp.131-139
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• 2023

Ascorbic acid plays a crucial role in the regulation of neurotransmitters and enzymes in the central nervous system. Maintaining an optimal level of ascorbic acid, which is between 0.6-2 mg/dL, is vital for preventing oxidative stress and associated health conditions, such as cancer, diabetes, and liver disease. Therefore, the detection of ascorbic acid is of the utmost importance. Electrochemical sensing has gained significant attention among the various detection methods, owing to its simplicity, speed, affordability, high selectivity, and real-time analysis capabilities. However, conventional electrodes have poor signal response, which has led to the development of modified electrodes with better signal response and selectivity. Carbon nanotubes (CNTs) and their composites have emerged as promising materials for the electrochemical detection of ascorbic acid. CNTs possess unique mechanical, electrical, and chemical properties that depend on their structure, and their large surface area and excellent electron transport properties make them ideal candidates for electrochemical sensing. Recently, various CNT composites with different materials and nanoparticles have been studied to enhance the electrochemical detection of ascorbic acid. Therefore, this review aims to highlight the significance of CNTs and their composites for improving the sensitivity and selectivity of ascorbic acid detection. Specifically, it focuses on the use of CNTs and their composites in electrochemical sensing to revolutionize the detection of ascorbic acid and contribute to the prevention of oxidative stress-related health conditions. The potential benefits of this technology make it a promising area for future research and development.

• Journal of Soil and Groundwater Environment
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• v.28 no.5
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• pp.59-67
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• 2023

This review examined the current administrative policies and guidelines for management of reclaimed soils after remediation processes and proposed practical strategies to improve the potential value of the remediated soil as a resource. Three management practices are proposed to facilitate more efficient recycling of remediated soil; obligatory use, quality certification, and tracking of the remediated soils. If properly implemented in utilization of remediated soil, these strategies could contribute to enhancing public safety by assuring soil quality. Such administrative tools, for both suppliers and demanders, are expected to mitigate potential risks associated with the transactions of remediated soil. To enhance the quality assurance process, a soil quality certification combined with the soil health assessment index was proposed. The systematic integration of the suggested practices with soil health assessment can allow to produce optimal results, encompassing affordability, efficiency, and accessibility, which helps establishing more robust 'Remediated Soil Recycling Management System (RSRMS)'. Subsequent researches should be conducted to develop more effective policies that incorporate soil health assessment tools. The proposed management practices for remediated soil, coupled with soil health assessment, can be a pioneering effort to achieve such goals. By fostering an environmentally friendly policies, the sustainable utilization of remediated soil can be attained. Overall, the proposed strategies can provide a sound framework for responsible and sustainable soil management practices.

• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.198-206
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• 2024

Given the high theoretical capacity (1,675 mAh g^-1) and the inherent affordability and ubiquity of elemental sulfur, it stands out as a prominent cathode material for advanced lithium metal batteries. Traditionally, sulfur was sequestered within conductive porous carbons, rooted in the understanding that their inherent conductivity could offset sulfur's non-conductive nature. This study, however, pivots toward a transformative approach by utilizing diatom shell (DS, diatomite)-a naturally abundant and economically viable siliceous mineral-as a sulfur host. This approach enabled the development of a sulfurlayered diatomite/S composite (DS/S) for cathodic applications. Even in the face of the insulating nature of both diatomite and sulfur, the DS/S composite displayed vigorous participation in the electrochemical conversion process. Furthermore, this composite substantially curbed the loss of soluble polysulfides and minimized structural wear during cycling. As a testament to its efficacy, our Li-S battery, integrating this composite, exhibited an excellent cycling performance: a specific capacity of 732 mAh g^-1 after 100 cycles and a robust 77% capacity retention. These findings challenge the erstwhile conviction of requiring a conductive host for sulfur. Owing to diatomite's hierarchical porous architecture, eco-friendliness, and accessibility, the DS/S electrode boasts optimal sulfur utilization, elevated specific capacity, enhanced rate capabilities at intensified C rates, and steadfast cycling stability that underscore its vast commercial promise.

• Korean Journal of Community Nutrition
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• v.29 no.1
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• pp.34-50
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• 2024

Objectives: Transformation through a sustainable food system to provide healthy diets is essential for enhancing both human and planetary health. This study aimed to explain about sustainable diets and illustrate appropriate measurement of adherence to sustainable diets using a pre-existing index. Methods: For literature review, we used PubMed and Google Scholar databases by combining the search terms "development," "validation," "sustainable diet," "sustainable diet index," "planetary healthy diet," "EAT-Lancet diet," and "EAT-Lancet reference diet." For data presentation, we used data from National Health and Nutrition Examination Survey, 2017-2018, among adults aged 20 years and older (n = 3,920). Sustainable Diet Index-US (SDI-US), comprising four sub-indices corresponding to four dimensions of sustainable diets (nutritional quality, environmental impacts, affordability, and sociocultural practices), was calculated using data from 24-hour dietary recall interview, food expenditures, and food choices. A higher SDI-US score indicated greater adherence to sustainable diets (range: 4-20). This study also presented SDI-US scores according to the sociodemographic status. All analyses accounted for a complex survey design. Results: Of 148 papers, 16 were reviewed. Adherence to sustainable diets fell into 3 categories: EAT-Lancet reference diet-based (n = 8), Food and Agriculture Organization (FAO) definition-based (n = 4), and no specific guidelines but including the sustainability concept (n = 4). Importantly, FAO definition emphasizes on equal importance of four dimensions of diet (nutrition and health, economic, social and cultural, and environmental). The mean SDI-US score was 13 out of 20 points, and was higher in older, female, and highly educated adults than in their counterparts. Conclusions: This study highlighted that sustainable diets should be assessed using a multidimensional approach because of their complex nature. Currently, SDI can be a good option for operationalizing multidimensional sustainable diets. It is necessary to develop a Korean version of SDI through additional data collection, including environmental impact of food, food price, food budget, and use of ready-made products.

• Journal of Veterinary Science
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• v.25 no.2
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• pp.28.1-28.11
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• 2024

Background: Porcine circovirus type 2 (PCV2) infection is ubiquitous around the world. Diagnosis of the porcine circovirus-associated disease requires clinic-pathological elements together with the quantification of viral loads. Furthermore, given pig farms in regions lacking access to sufficient laboratory equipment, developing diagnostic devices with high accuracy, accessibility, and affordability is a necessity. Objectives: This study aims to investigate two newly developed diagnostic tools that may satisfy these criteria. Methods: We collected 250 specimens, including 170 PCV2-positive and 80 PCV2-negative samples. The standard diagnosis and cycle threshold (Ct) values were determined by quantitative polymerase chain reaction (qPCR). Then, two point-of-care (POC) diagnostic platforms, convective polymerase chain reaction (cPCR, qualitative assay: positive or negative results are shown) and EZtargex (quantitative assay: Ct values are shown), were examined and analyzed. Results: The sensitivity and specificity of cPCR were 88.23% and 100%, respectively; the sensitivity and specificity of EZtargex were 87.65% and 100%, respectively. These assays also showed excellent concordance compared with the qPCR assay (κ = 0.828 for cPCR and κ = 0.820 for EZtargex). The statistical analysis showed a great diagnostic power of the EZtargex assay to discriminate between samples with different levels of positivity. Conclusions: The two point-of-care diagnostic platforms are accurate, rapid, convenient and require little training for PCV2 diagnosis. These POC platforms can discriminate viral loads to predict the clinical status of the animals. The current study provided evidence that these diagnostics were applicable with high sensitivity and specificity in the diagnosis of PCV2 infection in the field.

• Journal of agricultural medicine and community health
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• v.11 no.1
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• pp.44-54
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• 1986

This study was aimed at investigating the health seeking behaviors of patients; For the purpose of analyzing the research theme we classified the study into two phase. First, the types of patients' health seeking behavior were categorized into a scheme according to what medical care resources were utilized in patients' coping process. Second, from patients' first visits to third visits to medical resources, we analyzed variations of factors which noted as crucial elements in constituting the patients' sickness career. To grasp the generalized characteristics from complicated empirical data, we limited the scope of our analysis to third stage of health seeking. A total of 121 persons who had beer suffering from chronic diseases more than 3 months was sampled among the residents of Banwol-Eup, the target Area of Korea University Health Project. The findings are as follows ; 1) In the course of visiting medical care resources, 34 different types of health seeking Behavior were found. From this result we inferred the idea that patients in Banwol-Eup had not any stable norms to cope with their pains. Clinics, hospital, pharmacy, Herb-doctors', folkways (self-treatment) were accessed by patients in orders. But more than half of patients who had utilized clinics or hospitals from their first to third visits, changed medical care resources to others, for example herb doctors or folkways, which had fundamentally different treatment models. Upon these two facts, the diversified types and capricious patterns in the health seeking behavior of Banwol patients, we observed a typical Shopping-Around phenomenon. 2) Factors which influenced patients' to their sickness career were changed along the courses of health seeking, from first to third visits as follows ; $\cdot$ Perceived seriousness of diseases were tended to decrease. $\cdot$ Professional medical personnel tended to be influencial in the patients' sickness career, (5.0%, 25.0% and 65.7%). The influence of the primary interaction groups such as parents, friends, neighbours, tended to decrease ; (90.9%, 71.2% and 30.0%). $\cdot$ The subjective reasons why to choose such a medical care resource were related to economic affordability and disease-itself as main motives. Credibility of health resources tended to increase 14.9%, 24.0% and 31.4 sequently. $\cdot$ Geographic accessibility factors did not change significantly. Most of patients had utilized health resources in Banwol and Anyang area. 3) Cultural inclination in the shopping-around phenomenon has shown difference among age groups. The age group' over 50 years' preferred traditional health resources to modern health resources. 4) Consistency of health seeking behavior on the shopping around phenomenon has shown difference according to the degrees of patients' economic affordability and those of psychological satisfaction toward modern health services. However, there were some restrictions in this thesis ; a) the study was limited to the 3rd health seeking career so it did not allow us to collect more informations after that, b) the study was not able to carry out causal analysis on patients health behavior determinated by explanatory model of health resources, and c) the study was not able to take into consideration of factors connected with social structural circumstances. Despite of restrictions described above, we are sure that this thesis would promote health providers' understanding toward patients' inclinations, through which they could provide efficient and accurate medical service.