• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.1
• /
• pp.143-151
• /
• 2020

Recently, research on self-healing concrete has been actively conducted, and various methods have been attempted for use in the maintenance of structures. However, contrary to the technical development of self-healing concrete, the method for evaluating the performance is insufficient. Although surface observation and permeability experiments are widely used to observe the healing of cracks, microscopic observation of surface may be insufficient to assess the overall performance. Also, permeation experiments should consider the losses caused by the dissolution of self-healed product and viscosity of water. Although a gas diffusion experiment have been proposed to overcome the shortcomings of these two test methods, verification has not been made on specimens with actual healing. Therefore, in this study, gas diffusion experiments were performed on the mortar specimens that had healed, and the adequacy of self-healing evaluation by the gas diffusion experiment was verified.

• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.47.2-47.2
• /
• 2020

The Experiment to Detect the Global EoR Signature (EDGES) has probed the status of the early Universe through the global 21cm observation. The claimed (brightness temperature) of ~ 500 mK absorption dip at z~17 against the continuum background cannot be explained in the standard LambdaCDM framework. In the meantime, the Planck 2018 Legacy Data, especially the E-mode polarization power spectrum, puts rather strong constraints on the high-redshift reionization process. We show how these two observational contraints can be accomodated in a series of reionization scenarios, with a special focus on the strongly self-regulated reionization by first stars.

• Journal of the Microelectronics and Packaging Society
• /
• v.18 no.3
• /
• pp.53-57
• /
• 2011

In the modern packaging technologies highly condensed metal interconnects are typically formed by highcost processes. These methods inevitably require the precise controls of mutually dependant process parameters, which usually cause the difficulty of the change in the layout design for interconnects of chip to-chip, or chip-to-substrate. In order to overcome these problems, the unique concept and methodology of self-assembly even in micro-meter scale were developed. In this report we focus on the factors which influenced the self-formed bumps by analyzing the phenomenon experimentally. In case of RMA flux, homogenous pattern was obtained in both plain surface and cross-section surface observation. By using RA flux, the phenomena were accelerated although the self-formtion results was inhomogenous. With ussage of moderate RA flux, reaction rate of the self-formation was accelerated with homogeneous pattern.

• Korean Journal of Child Studies
• /
• v.20 no.1
• /
• pp.165-176
• /
• 1999

The purpose of this study was to investigate whether children's temperament and maternal control strategies were related to the self-control behaviors of 3-year-old children. The sample was comprised of 50 young children, ranging from 37 to 50 months of age, and their mothers. Mothers were asked to complete a questionnaire on children's temperament. Situational observation was conducted for obtaining data on maternal control strategies and for children's self-control behaviors in a resistance to temptation situation. All the subjects' activities were videotaped for 20 minutes. Differences were found in maternal control strategies and children's self-control behaviors by gender of child and by age and education of mothers. Relationships were found between children's temperament and maternal control strategies. However, children's temperament had an indirect effect on their self-control behaviors through maternal control strategies. The findings indicated that the self-control development of children in this sample were in a transitional stage.

• Journal of Fisheries and Marine Sciences Education
• /
• v.20 no.3
• /
• pp.343-357
• /
• 2008

Generally, schooling is implemented by instruction in the classroom. And instruction is made progress by concrete interaction through teacher's question and students' answer or presentation. According to a lot of researches on teacher-student interaction, student's opportunity of class presentation is influenced by students' self-esteem, learning attitude, academic achievement, and relationships. And students' opportunity of class presentation is very important not only students but also social equality and democracy. Therefore, teachers have to recognize the importance of students' opportunity of class presentation. However, according to many referential researches, students' opportunity of class presentation is differentiated by students' academic ability and social-economic status. The purpose of this study was to ascertain whether students' opportunity of class presentation was differentiated by students' academic ability and social-economic status or not. The method of this study was used checklist, interview, and class observation for a month. This study indicates that in spite of some exceptional cases, many students were taken the opportunity of class presentation differently by his/her academic ability and social-economic status. And teacher does not recognize that whether she gives student's opportunity of class presentation differently or not. To be a good teacher, teacher should reflect that teaching students is not easy, and teaching students is very important. And teacher should recognize that her speaking, action, and interaction with students including students' opportunity of class presentation influences students' self-esteem, learning attitude, academic achievement, and relationships.

• Journal of the Korea Institute of Building Construction
• /
• v.7 no.2 s.24
• /
• pp.99-106
• /
• 2007

The purpose of this study presents in Relations between cracks in self-leveling material and quality of floor groundwork surface are experimentally examined. As the first stage, the experiment to observe cracks in self-leveling material constructed on floor groundwork made from various kinds of concrete was carried. As a result, following basic findings were obtained. First, observation of cracks should be continued until an increase in width of cracks stop, without constructing any finishing material. Second, degree of cracks may be indicated quantitatively by the product of length and width. Finally, Cracks and separation is not be influenced by specimen size. Based on these findings, the method of predicting cracks by evaluating surface layer quality of floor groundwork will be established.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.2
• /
• pp.51-54
• /
• 2005

In this work, the attempt has been made to investigate the morphology of self-assembled dipyridinium dithioacetate on Au(111) substrate by Scanning Tunneling Microscopy(STM). Also, we measured electrical properties(I-V) using Scanning Tunneling Spectroscopy(STS). Sample used in this experiment is dipyridinium dithioacetate, which contains thiol functional group, this structure that can be self-assembled easily to Au(111) substrate. The self-assembly procedure was used for two different concentrations, 0.5 mM/ml and 1 mM/ml. Dilute density of sample by 0.5 mM/ml, 1 mM/ml and observed dipyridinium dithioacetate's image by STM after self-assembled on Au(111) substrate. The structure of STM tip-SAMs-Au(111) substrate has been used measurement for electrical properties(I-V) using STS. The current-voltage(I-V) measurement result, observed negative differential resistance(NDR) properties.

• Journal of Science Education
• /
• v.34 no.1
• /
• pp.105-112
• /
• 2010

The purpose of this research was to investigate relations between prior knowledge and primary grade science brilliant intellect's observation and inquiry. The subjects were selected 'Spider and cobweb' that self-regulation quest is available. Subjects were divided into two groups with one group having no prior knowledge about research subject. Compared observation method question type and level that appear between subject achievement to group. Target learning group are 5 ~ 6 school year 17 people for national university for the gifted center of local middle city. Researcher collected and analyzed data using summer vacation concentration education period. Source collection subject's research recording paper, subject's voice recording device, interview data etc. A data analysis tool took advantage of observation method that is studied in existing, question type, question level. Research was able to conclude : First, observation of prior knowledge happened than mass of students who many mass of students are few relatively vigorously. Second, primary grade science brilliant intellect students used more mainly manufacturing observation than simplicity observation that use senses regardless of relative quantity of prior knowledge. Third, prior knowledge expressed variety when many mass of students observe operation relatively.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.96.3-96
• /
• 2001

In this paper the self-organized and fuzzy inference used stochastic gradient ascent method is proposed. Fuzzy rule and fuzzy set increase as occasion demands autonomously according to the observation information. And two rules(or two fuzzy sets)becoming to be similar each other as progress of learning are unified. This unification causes the reduction of a number of parameters and learning time. Using fuzzy inference and making a rule with an appropriate state division, our proposed method makes it possible to construct a robust reinforcement learning system.

• Journal of Korean Elementary Science Education
• /
• v.35 no.2
• /
• pp.253-264
• /
• 2016

The purpose of this study was to investigate implications of self-directed learning experiments in elementary science education through understanding elementary school students' awareness of their experiences in self-directed learning experiments. Twenty students joined the school science club voluntarily and conducted self-directed learning experiments. We collected data through observation of the experiments, interviews, and questionnaires. The students who participated in the club showed high satisfaction with self-directed learning experiments. The participants were aware that their scientific interest and knowledge, and the confidence in conducting experiments were increased. The students felt positive about the inquiry process of conducting self-directed learning experiments with their own subjects. They also felt a sense of achievement in attempting their experiments in defiance of several failures. The participants realized that the self-directed inquires led to increased declarative and procedural knowledge of science. The students stated that they had some difficulties in coping with the different results contrary to expectations and preparing laboratory materials and instruments. Nonetheless, they showed the promotion of their scientific literacy during overcoming those difficulties. We suggest that self-directed learning experiments can be a more effective way in science learning to make students experience the nature of science than existing school experiments. This can be implemented through a creative experience activities such as science clubs.