• Smart Structures and Systems
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• v.29 no.1
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• pp.251-266
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• 2022

Structural Health Monitoring (SHM) of critical infrastructure comprises a major pillar of maintenance management, shielding public safety and economic sustainability. Although SHM is usually associated with data-driven metrics and thresholds, expert judgement is essential, especially in cases where erroneous predictions can bear casualties or substantial economic loss. Considering that visual inspections are time consuming and potentially subjective, artificial-intelligence tools may be leveraged in order to minimize the inspection effort and provide objective outcomes. In this context, timely detection of sensor malfunctioning is crucial in preventing inaccurate assessment and false alarms. The present work introduces a sensor-fault detection and interpretation framework, based on the well-established support-vector machine scheme for anomaly detection, combined with a coalitional game-theory approach. The proposed framework is implemented in two datasets, provided along the 1st International Project Competition for Structural Health Monitoring (IPC-SHM 2020), comprising acceleration and cable-load measurements from two real cable-stayed bridges. The results demonstrate good predictive performance and highlight the potential for seamless adaption of the algorithm to intrinsically different data domains. For the first time, the term "decision trajectories", originating from the field of cognitive sciences, is introduced and applied in the context of SHM. This provides an intuitive and comprehensive illustration of the impact of individual features, along with an elaboration on feature dependencies that drive individual model predictions. Overall, the proposed framework provides an easy-to-train, application-agnostic and interpretable anomaly detector, which can be integrated into the preprocessing part of various SHM and condition-monitoring applications, offering a first screening of the sensor health prior to further analysis.

• Journal of the Korean Chemical Society
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• v.58 no.4
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• pp.406-417
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• 2014

The importance of small group activity has recently been emphasized in the gifted education in science because of the increased needs to foster the human resources that could explore through the communication and collaboration. In this study, we investigated the characteristics of the verbal interaction according to the learning styles of the gifted-students in science in the small group activity and examined how learning style affected the interaction within a group in order to seek an effective grouping strategy. The competition, cooperative, and dependent students with learning style in the small group 1 and the cooperative, cooperative, dependent students in the small group 2 were assigned by the 6 science high school students. The analyses of the results revealed that the small group 1 showed the asymmetric interaction of the low level, whereas the small group 2 showed the symmetric interaction of the high level. In other words, the frequencies of in-depth interaction in the small group 2 were higher than those in the small group 1, and also students in the small group 2 were equally involved in the activity rather than the small group 1. These results suggested that the grouping by the students' learning styles in the small group activity should affect significantly the participation decision in activity and the level of verbal interaction. Educational implications of theses findings were discussed.

• Journal of the Korean Chemical Society
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• v.58 no.4
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• pp.393-405
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• 2014

The purpose of this study was to investigate the characteristics of social interaction on cultural aspects, verbal interaction, and discussion maps in scientific modeling instruction on combustion in middle school. Revised-CLEQ (Cultural Learning Environment Questionnaire), verbal interaction framework, discussion maps analysis were implemented for this study. The results of study follow respectively. First, the characteristics on cultural aspects of middle school students showed cooperation rather than competition in terms of collectivism. Students' attitudes to learning science tended to depend on others' idea, and students were passive and reluctant to present their comments when they were modeling work. Second, for the characteristics of verbal interaction, they simply presented knowledge related to build a model. The response to comments and feedback was relatively few. Third, discussion maps showed a lot of interaction for reponses that was alternatively brought the concept of commenters, which students were depended on a specific one, and responses. There were not many interaction for elaboration, which were described to have new presented ideas, corrections, and reasons when they exchange their ideas. In this study the model type of interaction affecting the formation of the students understanding of and in our country, it makes a lot of social interactions as the basis for teaching system could be utilized.

• Journal of Soil and Groundwater Environment
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• v.11 no.6
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• pp.76-82
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• 2006

Fenton's reaction are difficult to apply in the field due to the low pH requirements for the reaction and the loss of reactivity caused by the precipitation of iron (II) at neutral pH. Moreover, Fenton-like reactions using iron mineral instead of injection of iron ion as a catalyst are operated to get high removal result at low pH. Because hydroxyl radical can generate at the surface of iron mineral, there are competition with a lot of hydroxide at around neutral pH. On the other side, to operate Fenton's reaction series at neutral pH, modified Fenton reaction is suggested. The complexes, composed by iron ions (ferrous ion or ferric ion)-chelating agent, could be acted as a catalyst and presented in the solution at neutral pH. However, modified Fenton reaction requires a lot of hydrogen peroxide. Accordingly, the purpose of this experiment was to effectively combine Fenton-like reaction and modified Fenton reaction for extending application of Fenton's reaction. i.e., injecting chelating agents in Fenton-like reaction at around neutral pH is increasing the concentration of dissolved iron ion and highly promoting the oxidation effect. 2,4,6-trinitrotoluene (TNT) was used as a probe compound for comparing reaction efficiencies in this study. If the concentration of dissolved iron ion in combined Fenton process were existed more than 0.1 mM, the total TNT removal were increased. Magnetite-NTA system showed the best TNT removal (76%) and Magnetite-EDTA system indicated about 56% of TNT removal. The results of these experiments proved more promoted 40-60% of TNT removal than Fenton-like reaction's.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.310-311
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• 2011

Dual-frequency (DF) capacitively coupled plasmas (CCP) are used to separately control the mean ion energy and flux at the electrodes [1]. This separate control in capacitively coupled radio frequency discharges is one of the most important issues for various applications of plasma processing. For instance, in the Plasma Enhanced Chemical Vapor Deposition processes such as used for solar cell manufacturing, this separate control is most relevant. It principally allows to increase the ion flux for high deposition rates, while the mean ion energy is kept constant at low values to prevent highly energetic ion bombardment of the substrate to avoid unwanted damage of the surface structure. DF CCP can be analyzed in a fashion similar to single-frequency (SF) driven with effective parameters [2]. It means that DF CCP can be converted into SF CCP with effective parameters such as effective frequency and effective current density. In this study, comparison of DF CCP and its converted effective SF CCP is carried out through particle-in-cell/Monte Carlo (PIC-MCC) simulations. The PIC-MCC simulation shows that DF CCP and its converted effective SF CCP have almost the same plasma characteristics. In DF CCP, the negative resistance arises from the competition of the effective current and the effective frequency [2]. As the high-frequency current increases, the square of the effective frequency increases more than the effective current does. As a result, the effective voltage decreases with the effective current and it leads to an increase of the ion flux and a decrease of the mean ion energy. Because of that, the negative resistance regime can be called the preferable regime for solar cell manufacturing. In this preferable regime, comparison of DF (13.56+100 or 200 MHz) CCP and SF (60 MHz) CCP with the same effective current density is carried out. At the lower effective current density (or at the lower plasma density), the mean ion energy of SF CCP is lower than that of DF CCP. At the higher effective current density (or at the higher plasma density), however, the mean ion energy is lower than that of SF CCP. In this case, using DF CCP is better than SF CCP for solar cell manufacturing processes.

• Journal of Korea Foresty Energy
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• v.22 no.3
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• pp.11-19
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• 2003

Allelopathic effects of black locust(Robinia pseudoacacia L.) was evaluated through germination tests using 13 different species including R. pseudoacacia itself. The water extract from leaf or root of R. pseudoacacia was separately tested. Seed germination of several species was inhibited in the presence of leaf or root extract, although the level of germination was in a wide range depending on the species. Seed germination of R. pseudoacacia was suppressed by 30 % in its leaf extract. Among tested tree species, Hibiscus syriacus and Alnus frma showed significantly inhibited germination in the root extracts whereas Thuja orientalis exhibited germination inhibition in the leaf extract. HPLC was carried out to identify allelochemicals in extracts of leaf and root using eight authentic phenolic compounds that are known to be responsible for allelopathy. The major phenolic compounds occupying about 40 % of total phenolic acids were gentisic acid in leaves and vanillic acid and syringic acid in roots. The leaves contained 7 times more phenolic acids than the roots. Among 8 tested phenolic compounds vanillin was detected only in roots and coumaric acid in leaves. Consequently, 3 out of 13 species showed significantly inhibited germination due to leaf or root extract. This germination test indicates that the inhibitory allelopathic effect by R. pseudoacacia is caused by chemical interaction not by nutritional competition and that the allelochermicals of black locust act species-specifically. No specific influence of the total amount of phenolic compounds on the allelopathic inhibitory germination and the synergic effect by each phenolic compound may play a role for the allelopathic effect by R. pseudoacacia.

• Journal of the Korean Chemical Society
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• v.65 no.2
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• pp.133-144
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• 2021

Science teachers in elementary schools and secondary schools recognize the necessity of character education, feeling difficulties such as evaluation methods, mood of competition, extra work and lack of time according to previous research, which were based on answers from science teachers not experiencing character education. As a rare study of teacher experiencing, previous researches didn't fully address the problems and suggestions about adopting character education in science classrooms. This study is about teacher practice of character education on site with the CoProC (Collaborative Problem-Solving for Character Competence) program in science classes with which other previous studies shed new light. Five teachers, adapting the CoProC program in their science classes, participated in two interviews, sharing their student achievement in character education. Results showed that student achievement was high when their teacher had experienced the training program, development, and classes of CoProC rather than their normal teaching career. Teacher recognition on the aims of CoProC influenced difficulties, evaluation, and feedback.

• Food Science and Industry
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• v.52 no.2
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• pp.188-201
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• 2019

In the past, food additives were classified and managed as chemical synthetic and natural additives according to the manufacturing process, but it was difficult to confirm the purpose or function of food additives.CODEX, an internationalstandard, classifies food additives according to their practical use, based on scientific evidence on the technical effects of food additives, instead of classifying them as synthetic or natural. Therefore, very recently, the food additive standards in Korea have been completely revised in accordance with these global trends. Currently, the classification system of food additives is divided into 31 uses to specify their functions and purposes instead of manufacturing methods. Newer revision of the legislative framework for defining and expanding the scope of the Act as an enlarged area is required. Competition for preempting new food products based on bio-based technology is very fierce in order to enhance the safety of domestic people and maximize the economic profit of their own countries. In this age of infinite competition, it is very urgent to revise or supplement the current regulations in order to revitalize the domestic food industry and enhance national competitiveness through the development of food additives using new biotechnology. In this report, current laws on domestic food ingredients, food additives and manufacturing methods, and a comparison of domestic and foreign advanced countries' regulations and countermeasures strategies were reviewed to improve national competitiveness of domestic advanced biotechnology-based food additives industry.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.554-560
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• 2014

To investigate the applicability of montmorillonite to capping material for the remediation of contaminated marine sediment, adsorption characteristics of $PO{_4}{^{3-}}$ onto montmorillonite were studied in a batch system with respect to changes in contact time, initial concentration, pH, adsorbent dose amount, competing anions, adsorbent mixture, and seawater. Sorption equilibrium reached in 1 h at 50 mg/L but 3 h was required to reach sorption equilibrium at 300 mg/L. Freundlich model was more suitable to describe equilibrium sorption data than Langmuir model. The $PO{_4}{^{3-}}$ adsorption decreased as pH increased, due to the $PO{_4}{^{3-}}$ competition for favorable adsorption site with OH- at higher pH. The presence of anions such as nitrate, sulfate, and bicarbonate had no significant effect on the $PO{_4}{^{3-}}$ adsorption onto the montmorillonite. The use of the montmorillonite alone was more effective for the removal of the $PO{_4}{^{3-}}$ than mixing the montmorillonite with red mud and steel slag. The $PO{_4}{^{3-}}$ adsorption capacity of the montmorillonite was higher in seawater than deionized water, resulting from the presence of calcium ion in seawater. The water tank elution experiments showed that montmorillonite capping blocked well the elution of $PO{_4}{^{3-}}$, which was not measured up to 14 days. It was concluded that the montmirillonite has a potential capping material for the removal of the $PO{_4}{^{3-}}$ from the aqueous solutions.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.1
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• pp.20-28
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• 1999

Nine soil media when placed over a plastic sheet with three seeding rates were evaluated for influence on covering rate, height, growth, surface hardness, tear strength and sod establishment of Kentucky bluegrass. 1. Bark, peat and vermiculite over a plastic sheet had good effect in terms of the establishment of Kentucky bluegrass sod. 2. The good establishment of Kentucky bluegrass sod grown on bark, peat and vermiculite over a plastic sheet seemed to be caused by physical and chemical properties of each soil medium. 3. Sand, sandy loam, perlite and peatmoss caused poor effects on the covering rate, the growth, and the tear strength of Kentucky bluegrass. 4. Optimum seeding rate was $10g/m^2$ in terms of density and competition. 5. Good quality sod more depended on soil media than on seeding rates in this study.