• Advanced Composite Materials
• /
• v.17 no.3
• /
• pp.259-275
• /
• 2008

This study aims to optimize the mechanical and electrical properties of electrically conductive polymer composites (CPCs) for use as a material of bipolar plates for PEM fuel cells. The thin CPCs consisting of conductive fillers and polymer resin were fabricated by a preform molding technique. Expanded graphite (EG), flake-type graphite (FG) and carbon fiber (CF) were used as conductive fillers. This study tested two types of CPCs, EG/FG filled CPCs and EG/CF filled CPCs, to optimize the material properties. First, the characteristics of EG/FG filled CPCs were investigated according to the FG ratio for 7 and $100{\mu}m$ sized FG. CPCs using $100{\mu}m$ FG showed optimal material properties at 60 wt% FG ratio, which were an electrical conductivity of 390 S/cm and flexural strength of 51 MPa. The particle size was an important parameter to change the mechanical and electrical behaviors. The flexural strength was sensitive to the particle size due to the different levels of densification. The electrical conductivity also showed size-dependent behavior because of the different contributions to the conductive network. Meanwhile, the material properties of EG/CF filled CPCs was also optimized according to the CF ratio, and the optimized electrical conductivity and flexural strength were 290 S/cm and 58 MPa, respectively. The electrical conductivity of this case decreased similarly to the EG/FG filled case. On the other hand, the behavior of the flexural strength was more complicated than the EG/FG filled case, and the reason was attributed to the interaction between the strengthening effect of CF and the deterioration of voids.

• Journal of Korean Society of Forest Science
• /
• v.59 no.1
• /
• pp.121-142
• /
• 1983

Recently mycorrhizal research has been one of the most fast-growing research areas in modern plant science and microbiology. The application potential of mycorrhizal techniques to agriculture and forestry is enormous in view of the ubiquitous nature of mycorrhizae and known benefits of mycorrhizae to host plants. Unfortunately, very few scientists in Korea are currently involved in mycorrhizal research. When a team of American plant pathologists visited Korea in September 1982 to participate in the Korea-U.S.A. Joint Seminar on Forest Diseases and Insect Pests, they were surprised by the principal author's statement that there was no single research project on mycorrhizae sponsored by Korean government or any scientific institutions. The author initiated a few years ago a research project on the ecology of tree mycorrhizae with a foreign financial support. Major areas of interest were survey of ectomycorrhizae in relation to soil fertility, taxonomic distribution of mycorrhizae among woody plants, identification of ectomycorrhizal fungi, and growth response of woody plants to artificial inoculation. In spite of the enormous application potential of mycorrhizae to agronomic plants, the subject of mycorrhizae has not been recognized by Korean agronomists, foresters or pathologists. The purpose of this review rather written in Korean is to introduce the techniques of mycorrhizal research to Korean scientists and to urge them to participate in challenging new scientific field which might bring us a remarkable increase in crop productivity and tree growth through manipulation of this unique symbiosis. In this review, following topics were discussed in the same order: introduction; brief history of mycorrhizal research; morphology and classification of mycorrhizae; distribution of mycorrhizae in plant kingdom and in soil profile; physiology of mycorrhizae (functions, mineral nutrition, mycorrhizal formation); interaction of mycorrhizae with soil-born plant pathogens. mycorrhizae in nitrogen-fixing plants; application of mycorrhizal techniques to nursery practices (isolation, culture, inoculation, and response); prospect in the future.

• KSBB Journal
• /
• v.17 no.1
• /
• pp.20-25
• /
• 2002

We performed a basic experiment for rapid, on-line, real-time measurement of HBsAg by using a surface plasmon resonance biosensor to quantify the recognition and interaction of biomolecules. We immobilized the anti-HBsAg polyclonal antibody to the dextran layer on a CM5 chip surface which was pre-activated by N-hydroxysuccinimide for amine coupling. The binding of the HBsAg to the immobilized antibody was measured by the mass increase detected by the change in the SPR signal. The binding characteristics between HBsAg and its antibody followed typical monolayer adsorption isotherm. When the entire immobilized antibody was interacted, there was no additional, non-specific binding observed, which suggested the biointeraction was very specific as expected and independent of the ligand density. No significant steric hindrance was observed at 17.6 nm/$mm^2$ immobilization density. The relationship between the HBsAg concentration in the sample solution and the antigen bound to the chip surface was linear up to ca. $40\mu\textrm{g}$/mL, which is much wider than that of the ELISA method. It appeared the antigen-antibody binding was increased as the immobilized ligand density increased, but verification is warranted. This study showed the potential of this biosensor-based method as a rapid, simple, multi-sample, on-line assay. Once properly validated, it can serve as a more powerful method for HBsAg quantification replacing the current ELISA method.

• Journal of Digital Contents Society
• /
• v.18 no.8
• /
• pp.1585-1591
• /
• 2017

In this study, we propose the application of exhibition contents using virtual environment technology in exhibition space. Research on the virtual environment is continuing. Particularly, research on virtual reality technology is one of the most active research fields. As researches and developments of augmented reality technologies have been carried out with the spread of smart phones, researches on virtual reality technologies have also made a lot of progress with emphasis on games and interactivity. Especially, development of hardware, software, and content is accelerating this year, including the development of various types of physical reality devices, especially HMD (Head Mounted Device) equipment and new product announcements. We want to study and apply the environment in which the system based on this virtual reality technology can approach and experience more user friendly in the exhibition space.

• Korean Medical Education Review
• /
• v.16 no.3
• /
• pp.126-131
• /
• 2014

The purpose of this study is to analyze the medical education system of Korea and to propose a method of curriculum redesign. Although there have been many attempts by medical educators to improve the quality of medical education, the results have not been fruitful. First, there exists a limitation to the dualistic curriculum design based on Flexnerianism, and thus, this model does not provide an integrated experience to medical students. Therefore, we propose a unidimensional model for curriculum redesign. Second, it is impossible to promote excellence in medical education without solving the structural problems of teaching and learning, such as the teaching competency of the faculty, large-scale lectures, and team teaching systems. A curricular strategy that emphasizes mutual interaction and teaching accountability is necessary to promote meaningful learning. Third, the current clinical training system, the circulation model, provides incomplete training as well as a lack of sequence and articulation experiences. This system needs to be redesigned in a way that allows only those students who have mastered both the knowledge and the application of medical education to advance to the next step. Fourth, norm-referenced assessments of a medical college distort the learning process and create unconstructive system energy. A criterion-referenced assessment that values cooperation, independent study, and intrinsic motivation is more important for the reliability and validity of the assessment. Medical students should not focus on formative and informative learning. Medical colleges should investigate the multifaceted potential of the students and provide transformative learning to grow students into change agents. For this to take place, curriculum redesign-not new methods of medical education-is required.

• Journal of the Ergonomics Society of Korea
• /
• v.27 no.4
• /
• pp.109-117
• /
• 2008

Compared to the existing PC which uses a mouse and a keyboard, the touchscreen-based portable PC allows the user to use fingers, requiring new operation methods. However, current touchscreen-based web browser operations in many cases involve merely having fingers move simply like a mouse and click, or not corresponding well to the user's sensitivity and the structure of one's index finger, making itself difficult to be used during walking. Therefore, the goal of this study is to develop finger gestures which facilitate the interaction between the interface and the user, and make the operation easier. First, based on the frequency of usage in the web browser and preference, top eight functions were extracted. Then, the users' structural knowledge was visualized through sketch maps, and the finger gestures which were applicable in touchscreens were derived through the Meaning in Mediated Action method. For the front/back page, and up/down scroll functions, directional gestures were derived, and for the window closure, refresh, home and print functions, letter-type and icon-type gestures were drawn. A validation experiment was performed to compare the performance between existing operation methods and the proposed one in terms of execution time, error rate, and preference, and as a result, directional gestures and letter-type gestures showed better performance than the existing methods. These results suggest that not only during the operation of touchscreen-based web browser in portable PC but also during the operation of telematics-related functions in automobile, PDA and so on, the new gestures can be used to make operation easier and faster.

• The Journal of the Convergence on Culture Technology
• /
• v.4 no.1
• /
• pp.119-128
• /
• 2018

In this paper, The purpose of this qualitative research was to explore the experience of a nursing simulation practice focused on patients with cardiac arrest with 50 4th-year nursing students who participated the simulation practical education. The data collection period was from 12/4/2017 to 12/6. Subjects were asked to write a self-reflection journals with a narrative style in order to explore the cardiac arrest simulation practice experience. Data were analyzed using Thematic Analysis by Braun & Clarke. The results were "Expectation for types of simulation education", "A great deal of regret", "Pre-experience in cardiac arrest situation", "Cognition in the importance of team interaction", "Active reaction", "Extended role from a nursing student to a nurse." The results indiate that understanding the experience of a nursing simulation education for nursing students will be able to be used as baseline data which is needed to manage the method of the simulation education effectively.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.1
• /
• pp.63-68
• /
• 2004

Sugar-based gelator p-dodecanoyl-aminophenyl- ${\beta}$-D-aldopyranosides (1-3) have been shown to self-assemble in the presence of p-aminophenyl aldopyranosides. The hydrogel 1+4 showed the double-helical structure with 3-25 nm outer diameters, which is quite different from that of 1. The gel 2+5 revealed twisted ribbon structure with 30-50 nm in widths and a few micrometers of length whereas the gel 3+4 revealed the single and the bundled fiber structures. The difference in these gel supramolecular structures has successfully been transcribed into silica structures by sol-gel polymerization of tetraethoxysilane (TEOS), resulting in the doublehelical, the twisted-ribbon, the single and the multiple (lotus-shaped) hollow fiber structures. These results indicate that novel silica structures can be created by transcription of various superstructures formed in binary gels through the hydrogen-bonding interaction, and the amino group of the p-aminophenyl aldopyranosides acts as an efficient driving force to create novel silica nanotubes. Furthermore, electron energy-loss spectroscopy (ELLS) provided strong evidence for the inner hollow structure of the double-helical silica nanotube. This is a novel and successful example that a variety of new silica structures can be created using a library of carbohydrate gel fibers as their templates.

• Korean Journal of Clinical Pharmacy
• /
• v.23 no.1
• /
• pp.49-56
• /
• 2013

Objective: The purpose of this study was to evaluate the patterns of Over-the-Counter (OTC) drugs and their interactions with prescription drugs in adults visiting a community pharmacy. Method: The subjects were 151 adults aged over 20 years visiting a community pharmacy in Asan-si from December 16th 2011 to February 1st 2012. We used a survey questionnaire. The survey inquired about the prevalence and the details of any OTC drug use and the characteristics of the study subjects. The drug interaction classification system from Lexicomp's Lexi-interact data fields was used to identify OTC drugs likely to have clinically significant interactions with prescription drugs. Results: The patterns of OTC drug use were related to thirties (from 30 to 40 years old), female gender, higher education, non-smoking, sometimes use of alcohol, and self-perceived normal health status. The most commonly used OTC drug category was antipyretic-analgesics (n=104, 53.3%), and the most commonly used ingredient was acetaminophen (n=67, 64.4%). The biggest motivation for taking OTC drugs was suggestion by pharmacists, reported by 55.6%. After reviewing each patient's prescription drugs and OTC drugs, 14 patients (36.8%) of 38 patients using prescription drugs were taking drug combinations with potential for clinically significant interactions. The concomitant use of OTC drugs with prescription drugs may lead to increased potentially harmful interactions. Conclusion: It is suggested that health-care professionals should be more aware of the potential and possible interactions and take into better account their patients' OTC drug use.

• Journal of the Korea Convergence Society
• /
• v.8 no.6
• /
• pp.209-218
• /
• 2017

Flipped Learning is being suggested which is well known as a teaching method which lets students learn the contents they will learn in advance through the advance online video and have a discussion through the team interaction in the main class for them to solve the assignment through the cooperation in a self-initiated way. Therefore, this study was intended to confirm if the flipped learning class could improve the students' learning ability and raising the interest in math by complementing the problem on the lecture-type class by applying the flipped learning class to the college basic math subject. As a result, in the unit test result, the average score of the experimental group was more than 20 higher than one of the control group indicating that Flipped Learning had a great effect on improving the learning ability, and as for the introspection journal analysis, many subjects from the experimental group showed the positive attitude toward math they felt difficult unlike ones from control group indicating that it was effective in improving the interest level.