• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.33 no.2
• /
• pp.45-53
• /
• 2023

The growth of Si on 4H-SiC substrate has a wide range of applications as a very useful material in power semiconductors, bipolar junction transistors and optoelectronics. However, it is considerably difficult to grow very fine crystalline Si on 4H-SiC owing to the lattice mismatch of approximately 20 % between Si and 4H-SiC. In this paper, we report the growth of a Si epilayer by an Al-related nanostructure cluster grown on a 4H-SiC substrate using a mixed-source hydride vapor phase epitaxy (HVPE) method. In order to grow hexagonal Si on the 4H-SIC substrate, we observed the process in which an Al-related nanostructure cluster was first formed and an epitaxial layer was formed by absorbing Si atoms. From the FE-SEM and Raman spectrum results of the Al-related nanostructure cluster and the hexagonal Si epitaxial layer, it was considered that the hexagonal Si epitaxial layer had different characteristics from the general cubic Si structure.

• Korean Journal of Culture and Social Issue
• /
• v.18 no.1
• /
• pp.79-96
• /
• 2012

The main studying problem of this study is to develop the scale which examines awareness of singleness for Korean men and women. So, firstly, study 1 fulfilled open survey related to condition for solitary life, its strengths and weaknesses and factors disturbing it for 490 unmarried and married people (244 men and 246 women) who are living in Seoul and capital area. And then, content analysis and category analysis were analyzed for their responses. As the result, each questionnaire was divided into economic aspect, relative aspect, characteristic aspect, eco related aspect, family aspect and social system aspect. Study 2 organized questionnaires for condition for solitary life, its strengths and weaknesses based on the material obtained in study 1 and then, exploratory factor analysis was conducted for total 800 adults (400 men and 400 women) who are living in Seoul, capital area, Incheon and Chungnam. As the result, the condition for solitary life extracted 5 factors including ego-maturity factor (24 questionnaires, total explanation quantity: 61.7%), strengths of solitary life extracted 6 factors including self-growth factor(29 questionnaires, total explanation quantity: 61.4 %) and weaknesses of solitary life extracted 6 factors including solitary factor(31questionnaires, total explanation quantity: 64.75 %). For verifying the suitability of the factor structure, as the result of conducting confirmatory factor analysis for 400 people (200 men and 200 women), the suitability of awareness scale model of men and women on singleness was verified. Those results were discussed from the aspect of variables and phenomenon related to singleness and marriage of Korean society.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.4
• /
• pp.416-424
• /
• 2023

Concrete emits a large amount of carbon dioxide throughout its life cycle, and due to the societal demand for carbon dioxide reduction, research on storing carbon dioxide in concrete in the form of minerals is ongoing. In this study, cyanobacteria, which absorb carbon dioxide through photosynthesis and fix it as calcium carbonate, were applied to a porous concrete substrate, and the changes in the properties of the concrete substrate due to their special environmental curing condition were analyzed. The results showed that the calcium carbonate precipitation by the microorganisms was concentrated in the light-exposed surface area, and most of the precipitation occurred in the cement paste part, not in the aggregate. This microbially induced calcium carbonate precipitation enhanced the mechanical performance of the paste and improved the overall compressive strength as the curing age progressed. In addition, the increase in microbial biofilm and calcium carbonate improved the pore structure, which influenced the reduction in water permeability.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.4
• /
• pp.509-516
• /
• 2023

The use of sulfur(S) in concrete has been variously studied as a way to improve salt resistance in concrete. However, sulfur is a solid material and is difficult to powder, which has disadvantages in its usability as an admixture or mixture for cement and concrete. For these problem, polymers such as dicyclopentadiene have been used to modify sulfur, but this also exists in a sticky state after modifying and does not improve the fundamental problem. So, reforming sulfur with slaked lime and the effect on cement hydration was examined by reforming sulfur with slaked lime, and the following conclusions were obtained. Depending on the reaction conditions, slaked lime modified bio-sulfur exists in a slurry state containing unreacted sulfur, unreacted slaked lime, calcium-sulfur(Ca-S) compounds and water. When slaked lime modified bio-sulfur is used as a cement mixture, salt resistance of concrete with slaked lime modified bio-sulfur is to be superior to that of plain concrete. This is believed to be because structure of cement hydrates with slaked lime modified bio-sulfur is to be more dense to that of plain cement hydrates by the continued presence of ettringite and can be used as a cement mixture in concrete.

• Membrane Journal
• /
• v.33 no.6
• /
• pp.362-368
• /
• 2023

This research article explores the application of Polymer of Intrinsic Microporosity (PIM-1) as a cutting-edge material for CO₂ gas separation membranes in response to the escalating global concern over climate change and the imperative to reduce greenhouse gas emissions. The study delves into the synthesis, molecular weight control, and fabrication of PIM-1 membranes, providing comprehensive insights through various characterization techniques. The intrinsic microporosity of PIM-1, arising from its unique crosslinked and rigid structure, is harnessed for selective gas permeation, particularly of carbon dioxide. The article emphasizes the tunable chemical properties of PIM-1, allowing for customization and optimization of gas separation membranes. By controlling the molecular weight, higher molecular weight (H-PIM-1) membranes are demonstrated to exhibit superior CO₂ permeability and selectivity compared to lower molecular weight counterparts (L-PIM-1). The study's findings highlight the critical role of molecular weight in tailoring PIM-1 membrane properties, contributing to the advancement of next-generation membrane technologies for efficient and selective CO₂ capture-an essential step in addressing the pressing global challenge of climate change.

• Journal of the Microelectronics and Packaging Society
• /
• v.30 no.3
• /
• pp.78-82
• /
• 2023

A fabrication of smart windows with controllable visible light transmittance in three steps by using λ/2 retardation films based on a reactive mesogen (RM) material and polarizing films is demonstrated. The phase retardation films with a Δn·d value of λ/2 (λ: wavelength) convert the direction of a traveling light to the optical axis of the film symmetrically. In this work, the retardation characteristics according to the RM thickness were evaluated and henceλ/2 phase retardation film can be fabricated. The phase retardation film with Δn·d of 276.1 nm, which is close to λ/2 (=275 nm @550 nm), was fabricated. The light transmittance of a smart window with the structure of (polarizing film)/(glass)/(alignment layer)/(λ/2 retardation film) was measured in the transmission mode, half mode and blocking mode. The evaluation results show that the transmittance of the smart window can be controlled in three steps with 35.8%, 27.8%, and 18.2% at each mode, respectively. In addition, by fabricating a smart window with a size of 15×200 mm², the feasibility of use in various fields such as buildings and automobiles was verified.

• Korean Journal of Community Nutrition
• /
• v.28 no.6
• /
• pp.509-522
• /
• 2023

Objectives: This study is intended to develop a curriculum for kindergarten food and nutrition education aimed at preschool children, reflecting government policy and meeting the demands of preschool settings. Methods: Existing educational materials were analyzed, and key elements of the 2019 Revised Nuri Curriculum ("Nuri Curriculum") and Guidelines for Nutrition and Food Education in Kindergartens, Elementary, Middle, and High Schools ("Guidelines") were examined as foundational information for developing the curriculum for food and nutrition education. Results: Basing ourselves on the five domains of the Nuri Curriculum, "Physical Activity and Health," "Communication," "Social Relationships," "Art Experience," and "Natural Science Inquiry," we integrated three areas from the Guidelines, namely "Dietary Habits and Health," "Dietary Habits and Safety," and "Dietary Habits and Culture," to structure the curriculum for kindergarten food and nutrition education. Three specific domains, "Nutrition and Health," "Food and Culture," and "Safe Dietary Practices," were tailored for preschool children, each comprising core concepts, content elements, and educational materials. In the "Nutrition and Health" domain, core concepts such as "nutrition" were addressed through content elements such as "balanced eating" and "vegetables and fruit," while "health" included elements such as "eating regularly" and "nutrients for disease prevention," each with two educational content components. The "Food and Culture" domain focused on "food" with content on "local foods (vegetable-garden experience)" and "food culture" with content on "our dining table (rice and side dishes)," "our agricultural products," "global cuisine (multiculture)," and "considerate dietary practices," each with four educational content components. The "Safe Dietary Practices" domain included core concepts such as "hygiene" with content on "hand-washing habits" and "food poisoning management," and "safety" with content on "food labeling." Conclusions: The systematized curriculum for kindergarten food and nutrition education aligns with the Nuri Curriculum and is interconnected with the Guidelines. This curriculum can be used as foundational material for developing educational resources tailored to the characteristics of preschoolers, contributing to effective implementation in early childhood education.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.33 no.5
• /
• pp.167-173
• /
• 2023

Li₃V₂(PO₄)₃ and Li₃V₂(PO₄)₃/C composite with single phase monoclinic structure for the cathode materials are successfully synthesized by direct co-precipitation method using N₂H₄·H₂O as the reducing agent and alginic acid as the carbon source, and their electrochemical properties were compared. The particles with approximately 1~2 ㎛ size and the uniform spherical-like morphology of the narrow particle size distribution were obtained. In addition, the residual carbon can also improve the electrical conductivity. The Li₃V₂(PO₄)₃/C composite has improved initial specific discharge capacity and excellent cycle characteristics to maintain capacity stably than Li₃V₂(PO₄)₃. The results indicate that the reducing agent and carbon composite can affect the good crystallinity and electrochemical performance of the cathode materials.

• Journal of the Society of Disaster Information
• /
• v.19 no.4
• /
• pp.834-843
• /
• 2023

Purpose: The Serious Civil Accidents consist of the public use facilities, the public transports, and the material and its products. According to the Serious Civil Accidents of the Serious Accidents Punishment Act, it must be constructed the safety and health management framework and execution system. In this study. we are design the model of the Serous Civil Accidents management and action system. Method: Firstly, we review from 8^th article to 11^th article of the enforcement ordinance of the Serious Accidents Punishment Act. From the articles, we design the visual and structural management system supporting the Act. Result: The Serious Civil Accidents apply to the system is consisted of 6 monitoring modules and 4 kinds DB modules. Conclusion: The Serious Civil Accidents are managed by the private enterprises, local governments, and public institutions. Specially, the CEO of restaurants, cafes, et al, do not know the detail information related to the Act. Also in case of the local governments, there are many facilities related the Act. It is not easy to the construct the management framework of the Act. This study provides the simple management structure for the Act.

• Applied Chemistry for Engineering
• /
• v.34 no.6
• /
• pp.612-618
• /
• 2023

Modern society spends more than 80% of its daily life indoors, emphasizing the need for attention to indoor air pollution due to the improvement in living standards. In this study, the performance and reaction characteristics of the Pt/TiO₂ catalysts prepared by liquid-phase reduction for the removal of formaldehyde (HCHO), one of the indoor air pollutants, at room temperature without the need for additional light or heat were investigated. As a result, it showed that catalysts prepared by the same method showed approximately 40~80% various activities depending on the type of TiO₂. XRD, BET, and XPS analyses were performed to investigate the particle size, crystal structure, specific surface area, and O/Ti molar ratio of the support material, and it revealed that the correlation between the properties and performance was insignificant. To explore the oxidation reaction pathway of formaldehyde (HCHO), in situ DRIFT analysis using carbon monoxide and H₂-TPR was perfomed. The results revealed that the performance was demonstrated by the oxidation state of the active metal and the adsorption-desorption characteristics of the adsorbate species.