• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.291-302
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• 2021

The phytoplankton community in the estuarine system is affected by changes of physicochemical factors easily. The present study analyzed phytoplankton community distribution and similarity, in addition to exploring factors influencing variations in phytoplankton community structure in three lakes located in the Yeongsan River estuary from March 2014 to November 2017. We carried out non-multidimensional scaling (NMDS) and random forest analysis (RF) for comparing the pattern of phytoplankton distribution and the relationship between phytoplankton distribution and environmental variables. Similarity Percentage (SIMPER) and Analysis of Similarity (ANOSIM) were performed to figure out the similarity of phytoplankton community at each site of three lakes. From NMDS, Phytoplankton community distribution differed between Yeongsan and Gumho lakes, and the factors influencing the distribution of phytoplankton communities across the three lakes were water temperature, dissolved oxygen, total nitrogen (T-N), nitrate-N (NO₃-N), and conductivity. NO₃-N was a key factor influencing phytoplankton community structure in the three lakes based on RF. A total of 24 species were identified as indicator species in the three lakes studied, with the highest species numbers observed in Yeongsan Lake (13) and the lowest observed in Yeongam Lake (2). According to SIMPER and ANOSIM results, the phytoplankton community in Yeongsan and Yeongam lakes were similar, and they differed from those in Gumho Lake. In addition, the phytoplankton community structure varied across the study sites in the three lakes, indicating that water channels across the lakes a minor influence phytoplankton community distribution.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.285-293
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• 2022

Sampling gears for collecting fish are diverse, and the community of fish varies according to the selection and characteristics of the sampling gears. The present study compared the characteristics of fish communities in Yedang reservoir using four sampling gears (kick net, cast net, gill net, and fyke net). The kick net and cast net were inefficient in collecting the number of individuals. However, they increased the species diversity of fish inhabiting the waterfront. Although not many individuals were collected, the gill net mainly collected large fish. The largest number of individuals was collected in the fyke net, and the dominance was high due to the high species selectivity. Through Self-Organizing Map (SOM) analysis, large fish were collected in the gill net, whereas small fish were collected in the fyke net. The characteristics and efficiency of the fish differed depending on the sampling gears. It is expected that researchers will need to use it appropriately according to the characteristics of the sampling gears when investigating the fish community.

• Journal of The Korean Association For Science Education
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• v.40 no.3
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• pp.291-305
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• 2020

The purpose of this study is to examine whether and how the features of performance assessments implemented during integrated science classes are related to teachers' PCK. We observed and video recorded four high school teachers' performance assessment practices, interviewed them, and surveyed their PCK. An analysis of the data shows that the teachers' performance assessment practices differed in terms of assessment of process, diagnosis of student learning progress, feedback, degree of classroom interactions, and use of assessment criteria. In particular, the opportunities for students to participate in assessment actively and use of assessment for learning varied across teachers. Also, relational patterns among science teaching orientations, PCK and performance assessment practices were found. When a teacher aimed at teaching for both academic learning and scientific literacy, sophisticated PCK was shown and assessment practices were complex accordingly. When scientific literacy was emphasized PCK highlighted experiential learning and assessments were not clearly distinguished from learning activities. In contrast, when academic achievement was emphasized traditional teaching strategies and assessments were highlighted. Based on these findings a number of topics for professional development are suggested including strategies for students' active engagement in assessment, use and development of specific assessment criteria, strategies for assessing performance qualities, and intuitive assessment competency development. Further research topics are also suggested.

• Journal of The Korean Association For Science Education
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• v.18 no.3
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• pp.443-450
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• 1998

This study was performed to find the environmental factors of inquiry instruction perceived by secondary school science teacher. The instrument consisted of three domains such as teaching conditions, viewpoints of secondary school science teachers of environmental factors for inquiry instruction, and barrier and improve! rent factors of inquiry instruction. Teaching conditions between middle school and high school science teachers were not different significantly. Environmental factors of inquiry instruction of secondary school science teacher included five factors such as 'facilities and encouragement', 'amount of works and materials', 'teacher education and textbook', 'practice and knowledge' and 'perception of necessity and satisfaction'. And all factors except 'perception of necessity and satisfaction' were very low state for inquiry instruction. In the disturbant and improving factors, the critical factors were 'over students per class', 'textbook' and 'learning materials' for middle school science teachers, and 'over students per class', and 'entrance examination' for high school science teachers. Thus the development and diffusion of adequate inquiry learning materials may be helpful to practicing inquiry instruction as decrease of works and psychological charges, and it is needed to reorganize systematically and intensify pre- and in-service teacher education to practice inquiry instruction.

• Journal of The Korean Association For Science Education
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• v.33 no.2
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• pp.466-477
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• 2013

The purpose of this study is to explore the measurement of attitude towards science based on social constructivism and the application of this scale. The data were collected using questionnaires from 833 middle school students in the second grade. First, factor analysis were used to assess the construct validity of the scale of Reputation in Culture Border Crossings (R-CBC) developed by Krogh and Thomsen (2005). This finding indicated the construct validity of R-CBC scale based on social constructivism. Second, the correlation among two scales based on social constructivism and Test of Science-Related Attitudes (TOSRA) scale based on individual constructivism were investigated to examine the convergent validity and the discriminant validity. The R-CBC scale was correlated with Simpson-Troost Attitude Questionnaire (STAQ) scale but the R-CBC scale and TOSRA scale were not connected. Third, students' attitude toward science assessed by three forms of measurements were compared according to the choice of high school type. Students' attitude toward science measured by R-CBC scale and STAQ scale were different in three types of high school. This finding indicated that two scales based on social constructivism are useful measurements that can predict the choice of high school type.

• Journal of agriculture & life science
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• v.44 no.1
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• pp.33-42
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• 2010

This study was conducted to estimate the effects of breed, sex, Farm-Scale and environment on average daily gain, age at 90kg, backfat thickness, eye muscle area and lean percent of pig. The total number of pig used in this study was 30,525 head consisted of 5,902 Landrace, 18,022 Yorkshire, and 6,601 Duroc on 2004 to 2008. The covariance used in the model to adjust age at the final test. The average daily gain, age at 90kg, and lean percent were significantly superior in medium Farm-Scale. However Backfat thickness and Eye muscle Area were significantly superior in small Farm-Scale. In conclusion this study suggest that breed, sex, test year, test season, Farm-Scale and environment may affect to average daily gain, age at 90kg, backfat thickness, eye muscle area and lean percent. The study about the Farm-Scale has to do continually more than now, and this study will be contributed to development of the pig industry.

• Journal of The Korean Association For Science Education
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• v.39 no.1
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• pp.45-57
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• 2019

NOS education through the history of science is regarded effective. However, science teaching has been criticized for not considering the interest of the learners enough and providing the context of learning themes that hinder the understanding of NOS. This study intends to convey the NOS element through the rich context of storytelling. The theme of the story is the history of continental drift, in which, the debate of many scientists and Wegener's creativity are prominent. Of the various media that deliver storytelling, the most powerful medium that leads to personal immersion is computer games, and among many kinds of games, the main genre of storytelling is role-playing games (RPGs). We developed the science history role-playing game (SHRPG) focusing on continental drift. The game development procedure followed Kim's 4F process (2017), which consists of the Figure Out, Focus, Fun Design, and Finalize. The story was constructed based on the NOS elements of Lederman et al. (2002), namely creativity and imagination demand, subjectivity, socio-cultural personality and tentativeness, which are all present in the story of the continental drift theory. The mechanics and rules of the RPG included quests, rewards, quizzes, NOS scores, and rankings. In the final phase of development, the game developed was pilot tested four times. The results of the tests showed that students' understanding of NOS through SHRPG has increased, especially in the creativity domain. The students' satisfaction with the fun, sympathy, and immersion during the game was very high.

• Journal of the Korean Society of Earth Science Education
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• v.13 no.3
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• pp.238-252
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• 2020

In this study, we analyzed the types of rebuttals in the argument structure of learning contents in lesson plans constructed by Earth science preservice teachers, and then we explored examples of how they responded to resolving the rebuttal. As a result of analyzing preservice teachers' assignments, discussions, and interviews collected during a total of 20 hours of classes and group discussions for 5 weeks, all 5 types of rebuttals suggested by Verheij (2005) were identified. Through the data analysis, a total of 18 rebuttal cases derived, and these cases were classified into 3 types according to how preservice teachers solve the rebuttals in class. The conclusions and implications based on the results are as follows: First, this study provided empirical data that the thinking process of validating core elements of argumentation and processes of argumentation is actively taking place in preservice teachers' lesson planning using the argument structure, and expanded the scope of application of argumentation in science education research. Second, the argument structure of learning contents should be used to help teachers to come up with strategies to induce students' curiosity and devotion to learn science contents. Third, preservice teachers should have the opportunity to think about the nature of science, including the variability and uncertainty of scientific knowledge when they discover rebuttals and develop solutions to them. Based on these conclusions, implications and suggestions for science education and further research were suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.352-361
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• 2021

An underwater positioning method that can be applied to structures for underwater construction is being developed at the Korea Institute of Ocean Science and Technology. The method uses an extended Kalman filter (EKF) based on an inertial navigation system for precise and continuous position estimation. The observation matrix was configured to be variable in order to apply asynchronous measured sensor data in the correction step of the EKF. A Doppler velocity logger (DVL) can acquire signals only when attached to the bottom of an underwater structure, and it is difficult to install and recover. Therefore, a complex sensor device for underwater structure attachment was developed without a DVL in consideration of an underwater construction environment, installation location, system operation convenience, etc.. Its performance was verified through a water tank test. The results are the measured underwater position using an ultra-short baseline, the estimated position using only a position vector, and the estimated position using position/velocity vectors. The results were compared and evaluated using the circular error probability (CEP). As a result, the CEP of the USBL alone was 0.02 m, the CEP of the position estimation with only the position vector corrected was 3.76 m, and the CEP of the position estimation with the position and velocity vectors corrected was 0.06 m. Through this research, it was confirmed that stable underwater positioning can be carried out using asynchronous sensors without a DVL.

• Journal of the Korean earth science society
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• v.42 no.1
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• pp.1-10
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• 2021

Silicon (Si) is the second most abundant element in the crust and consists of three stable isotopes, 28Si (92.23%), 29Si (4.67%), and 30Si (3.10%). Si isotopes are widely studied worldwide as a proxy for the biogeochemical cycle of Si to reconstruct the paleoenvironment and paleoclimate. However, in Korea, there have been no studies on biogenic silica using Si isotopes. In this study, we carried out Si isotope measurements of giant diatoms, summarizing the previously reported alkali fusion methods and establishing the best Si separation method for biogenic silica. Samples were completely digested using alkali fusion at high temperatures, effectively separating Si using an AG® 50W-X8 cation exchange resin. To evaluate the precision and accuracy of our measurements, Si isotope standard material (NBS-28) and USGS reference materials (AGV-2, GSP-2, BHVO-2) were analyzed. The results are in excellent agreement with the reported values within the acceptable error. The Si isotope measurement method developed in this study is expected to help in understanding the paleoclimate and paleoenvironment by tracing the Si cycle.