• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.369-380
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• 2020

Most mono-crystalline silicon ingots are manufactured by the Czochralski (Cz) process. But If there are oxygen impurities, These Si-ingot tends to show low-efficiency when it is processed to be solar cell substrate. For making single-crystal Si- ingot, We need Czochralski (Cz) process which melts molten Si and then crystallizing it with seed of single-crystal Si. For melts poly Si-chunk and forming of single-crystalline Si-ingot, the heat transfer plays a main role in the structure of Cz-process. In this study to obtain high-quality Si ingot, the Cz-process was modified with the process design. The crystal growth simulation was employed with pulling rate and rotation speed optimization. Studies for modified Cz-process and the corresponding results have been discussed. The results revealed that using crystal growth simulation, we optimized the oxygen concentration of single crystal silicon by the optimal design of the pulling rate, rotation speed and melt charge level of Cz-process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.8-16
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• 2018

This study examined the long-term behavior of a roadbed using high-speed railway concrete track and roadbed measurement data and evaluated the long-term performance of the track and roadbed. Recently, high-speed railway track type has been adopted as a concrete slab. On the other hand, the concrete track is vulnerable to roadbed settlement. In the case of gravel tracks, it is easy to restore the original state by maintenance even if the roadbed settles. On the other hand, in the case of the concrete track, if excessive settlement of the roadbed occurs, cracks are generated continuously on the slabs and sleepers, resulting in greatly reduced usability. For this reason, it is difficult to restore the original state only by partial maintenance. In this paper, a long-term performance evaluation was carried out on a concrete track during operation by monitoring the measurement data of sensors buried from the beginning of construction for approximately 3 years after the high-speed railway opened. Performance evaluation methods include a performance evaluation of track/roadbed when the train passes, long-term track and roadbed performance evaluation, analysis of the track/roadbed effect on long-term settlement and analysis of the factors influencing long-term settlement. The trail response of KTX-Sancheon was greatest in the track/roadbed performance evaluation by train. The results of the long-term track and roadbed performance evaluation were measured within the standard values. The track and roadbed performance impact assessment with long-term settlement was strongly related to TCL settlement. The influences of the water content and groundwater level were verified by analyzing the external factors of long-term settlement. Through such a method, the stability of a track/roadbed can be secured.

• Korean journal of communication and information
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• v.37
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• pp.418-451
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• 2007

The current study examined the relationships between the adolescent's conflict resolution style and Big-Five personality factors, self-monitoring and self-esteem. Firstly, results showed that adolescent's big-five personality model affects their conflict resolution styles with their friends and peer group. In detail, the higher the neuroticism was, the stronger became the attack and avoidance strategies. The higher the extraversion was, the higher became the collaborative strategy and the lower became the attack and avoidance strategies. The higher the agreeableness was, the higher became the collaborative strategy and the lower became the attack strategy. The higher the conscientiousness was, the higher became the collaborative strategy and the lower became the avoidance strategy. The higher the openness to experience was, the higher became the collaborative strategy and the lower became the avoidance strategy. The higher the self-esteem was, the higher became the collaborative strategy and the lower became the avoidance and attack strategies. The higher the self-monitoring was, the higher became the collaborative strategy and the lower became the avoidance strategy. Secondly, the big-five personality factors also affected the adolescent's conflict resolution styles. The extraversion, conscientiousness, and agreeableness positively affected the collaborative strategy. The neuroticism was positively related with the attack strategy, whereas agreeableness was negatively affected the attack strategy. The neuroticism and agreeableness were positively related with the avoidance strategy, whereas the extraversion was negatively affected the avoidance strategy. Limitations and suggestions for future study were discussed thereafter.

• Journal of The Korean Association For Science Education
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• v.36 no.2
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• pp.303-315
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• 2016

Socioscientific issues (SSI), by their nature, are conceptually embedded in technology. Previous research reported that nature of technology (NOT), unlike nature of science, was quite explicitly manifested in SSI decision-making, and NOT could be a promising construct for promoting SSI reasoning. In this study, authors introduced an integrated conceptual framework for NOT, which consisted of four dimensions (i.e., artifacts, knowledge, practice and system) as diverse modes of technology. We adapted the framework to investigate students' conceptualizations of NOT in the context of various SSIs. Data was collected from 45 college students enrolled in a liberal arts course on science and technology. The students participated in a team project, where they prepared and led discussions for SSI topics in class. Seven topics concerning SSIs were selected by students themselves. The preparation and class discussion of each student group were audio-recorded, and final reports were also analyzed. As a result, NOT sub-components in the dimensions of artifacts and system were explicitly represented in most contexts of SSI with various ranges of understanding. Other sub-components under the dimensions of knowledge and practice were rarely or implicitly shown in the discussion. The depth of students' understanding on NOT varied. Implications for science education were discussed.

• The Journal of Information Systems
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• v.25 no.2
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• pp.1-25
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• 2016

Purpose The innovation capability nowadays has become increasingly prominent in the universities not only for schools but also for teachers. However, due to less attention to the knowledge utilization and management, also some objective constraints, which caused the low level of the innovation capacity for our universities teachers under the current development in China. Meanwhile, transactive memory system (TMS) and knowledge sharing are important contents in knowledge management. The combination of both systems will contribute to a much more comprehensive understanding and performance of knowledge management. The purpose of this study is to investigate the structural relationships between TMS, knowledge sharing, and innovation capability among Chinese university teachers' teams, and to propose the practical implication to integrate effectively internal knowledge of the team to improve innovation capability. Design/methodology/approach In order to exam and verify the hypothesis proposed, we developed a questionnaire with 16 survey items, and each item comes with a five-point Likert-type scale. Hyperlink of online questionnaire was shared through WeChat. It's collected 201 responses from 14 universities in China, and the responders are teaching groups' leaders. And all together 191 responses were filtered out as the valid samples. And we analyze the data set and test research hypotheses by using SPSS 22.0 and AMOS 22.0. Findings All hypotheses are supported. The results reveal that knowledge sharing plays an important role in this study as the mediating role. TMS is positively associated with the innovation capability. And the knowledge sharing plays a significant role as mediating value between them, and influences the TMS's effect on innovation capability. It's thus cleared that if our teachers could well communicate, exchange and collaborate with other teachers in the same group, the innovation capability among the teachers would be improved effectively.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.3
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• pp.35-49
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• 2014

In this study, the faunae before and after creating the Solbangjuk Wetland Ecological Park located in Jecheon-city were compared. As a result, the change of the fauna according to the creation of the park showed the phenomenon that the species having the strong wilderness are reduced and the rate of general species become higher. In addition, the species which receive the restrictions for moving such as mammals, amphibians and reptiles are being gradually decreased by the increased visitors owing to the creation of the park. Moreover because there was the case where group of fishes have died caused by discharging and working the water in the reservoir during the creation process of the park, the supplementation work for this is required. However, it showed that the insects sucking the honey from flowers in the composed flower garden after creating the park, and the aquatic insects which live in this park that the stable water system for the growth of wetland plants is maintained, are increased, respectively. As a result of this survey, because the reservoir for agriculture adjacent to the residential area is generally small, the securing of the habitat space for the wild animals living in this park when creating the ecological parks seems to be necessary. The countermeasure should be considered so that some areas of the reservoir can be maintained in their natural state by adjusting the visitors' trails and the position of facilities for in order to secure the habitat of the wild animals.

• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.445-454
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• 2016

With the increase of decrepit facilities, construction waste increased to a certain level and now the increase is more or less stabilized. Yet construction waste still constitutes the largest portion of the overall wastes. Also, it is inevitable to spend a huge amount of the national budget due to the aggravating shortage of aggregate caused by prohibition on collection of natural aggregates as well as due to the damage to the land and environment caused by development of the sources of aggregates. As a countermeasure to the situation, the Ministry of Land, Infrastructure and Transport promulgated the quality standard for recycled aggregate to manage the usage of recycled aggregate according to its quality. But use of recycled aggregate for the purpose of high added value still remains nominal. Therefore, this research aims to study the applicability of recycled aggregate concrete as structural concrete by evaluating the quality improvement effects and the performance of the recycled aggregate concrete including recycled fine aggregate and recycled coarse aggregate that have undergone carbonation for 4 days and 14 days respectively in the condition of 60% RH, 20% $CO_2$ and $20^{\circ}C$ temperature, suggested for carbonation modifying from the advance research. The result shows carbonation modify contributed to quality improvement with 0.91% decrease in absorption rate for recycled fine aggregate and 0.7% decrease in absorption rate for recycled coarse aggregate. The physical properties and durability of the recycled aggregate made of aggregate modified by carbonation showed results similar to general concrete, which confirmed the possibility of applying the recycled aggregate made of recycled aggregate modified by carbonation to structural concrete.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.341-348
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• 2016

At present, about 40 million tons of concrete is dismantled each year, which accounts for the largest portion of the total amount of construction waste with 60.8%. It is known about 97.5% of it is recycled. However, most of the usage of waste concrete is limited to lower value-added business areas, and considering the increasing amount of waste concrete generated due to the deterioration of structures, the need for converting waste concrete to structural concrete is urgent. Therefore, this study aims at estimating the period for the optimum carbonation reforming to improve the quality of recycled aggregate, by making use of the method of accelerated carbonation reforming of the bonding heterogeneous (cement paste and mortar) for the purpose of converting recycled aggregate to structural concrete. Based on the period appropriate for the heterogeneous thickness and each bonding thickness of recycled aggregate which was drawn from previous studies, the changes in the characteristics and physical properties of pore structure according to progress of accelerated carbonation were analyzed. The result shows that with the progress of carbonation, the pore volume and the percentage of water absorption of the bonding heterogeneous decreased and the density increased, which indicates improvement of the product quality. But after certain age, the tendency was reversed and the product quality deteriorated. Synthesizing the results of previous studies and those of the present study, this study proposed 4 days and 14 days respectively for the period for the optimum carbonation reforming of recycled fine aggregate and recycled coarse aggregate.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.329-340
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• 2016

Increase in demotion and repair works on buildings in the construction market generates a large amount of construction waste. Recycling of construction waste is important for saving of resources, preservation of environment and constant advance of the construction industry. Accordingly, the environmental and economic value of recycled aggregate, which is produced after waste concrete is crushed, is increasingly highlighted. It is generally known that compared to concrete made of ordinary aggregate, concrete made of recycled aggregate has low quality, and the low quality is dependent on the amount of the bonding heterogeneous (cement paste and mortar) as well as the amount of the pores within the bonding heterogeneous. Reports on carbonation mechanism shows that the pores of cement-based materials are filled up by the progress of carbonation. Therefore, this study aims at an estimation of the period for optimum carbonation reforming appropriate for the thickness of the bonding heterogeneous of recycled aggregate, based on carbonation mechanism, with a view to improving the product quality by means of filling up the pores of the bonding heterogeneous of recycled aggregate. This study drew the carbonation depth according to the passage of age by calculating the bonding ratio and bonding thickness of the bonding heterogeneous as against the particle size distribution of recycled aggregate as well as by chemical quantitative analysis according to the age of accelerated carbonation of mock-up samples imitating bonding heterogeneous. Based on the correlation between the age of accelerated carbonation and carbonation depth, this study also proposed the estimated period of carbonation reforming of recycled aggregate appropriate for the thickness of the bonding heterogeneous.

• Education of Primary School Mathematics
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• v.4 no.2
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• pp.111-125
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• 2000

This paper presents cross-national perspectives on challenges in implementing current mathematics education reform ideals. This paper includes detailed qualitative descriptions of mathematics instruction from unevenly successful second-grade classrooms both in Koran and in the U. S with regared to reform recommendations. Despits dramatic differences in mathematics achivement between Korean and the U.S student. problems in both countries with regard to mathematics education are perceived to be very similar. The shared problems have a common origin in teacher-centered instruction. Educational leaders in both countries have persistently attempted to change the teacher-centered pedagogy to a student-centered approach. Many teachers report familiarity with and adherence to reform ideas, but their actual classroom teaching practices do not reflect the full implications of the reform ideals. Given the challenges in implementing reform, this study explored the breakdown that may occur between teachers adoption of reform objectives and their successful incorporation of reform ideals by comparing and contrasting two reform-oriented classrooms in both countries. This comparison and contrast provided a unique opportunity to reflect on possible subtle but crucial issues with regard to reform implementation. Thus, this study departed from past international comparisons in which the common objective has been to compare general social norma of typical mathematics classes across countries. This study was and exploratory, qualitative, comparative case study using grounded theory methodology based on constant comparative analysis for which the primary data sources were classroom video recordings and transcripts. The Korean portion of this study was conducted by the team of four researchers, including the author. The U.S portion of this study and a brief joint analysis were conducted by the author. This study compared and contrasted the classroom general social norms and sociomathematical norms of two Korean and two U.S second-grade teachers who aspired to implement reform. The two classrooms in each country were chosen because of their unequal success in activating the reform recommendation. Four mathematics lessons were videotaped from Korean classes, whereas fourteen lessons were videotaped from the U.S. classes. Intensive interviews were conducted with each teacher. The two classes within each country established similar participation patterns but very different sociomathematical norms. In both classes open-ended questioning, collaborative group work, and students own problem solving constituted the primary modes of classroom participation. However in one class mathematical significance was constituted as using standard algorithm with accuracy, whereas the other established a focus on providing reasonable and convincing arguments. Given these different mathematical foci, the students in the latter class had more opportunities to develop conceptual understanding than their counterparts. The similarities and differences to between the two teaching practices within each country clearly show that students learning opportunities do not arise social norms of a classroom community. Instead, they are closely related to its sociomathematical norms. Thus this study suggests that reform efforts highlight the importance of sociomathematical norms that established in the classroom microculture. This study also provides a more caution for the Korean reform movement than for its U.S. counterpart.