• Korean Journal of Ecology and Environment
• /
• v.55 no.1
• /
• pp.35-48
• /
• 2022

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries(78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.

• Korean small business review
• /
• v.39 no.1
• /
• pp.1-39
• /
• 2017

The first generation of the business that had been founded in 1960~1970s faces the situation to consider the succession of the family business developed by devotion of their whole lives in the critical timing to the next generation. In the process of selecting the party of family business succession, it is required to consider a variety of succession types including smooth transfer to the other family member or the employee of the company, selling the company, or hiring external specialist. Foreign countries acknowledge the importance of the succession in the family owned company to perform multiple studies on the influential factors to the succession, distinction, and types of family business succession; and they utilize the results for the related policy development and the support of family owned business succession. However, few studies have been conducted on the succession of the domestic family owned business and majority of them are related to the types of succession. Considering its share and influential power in the domestic economy, it is necessary to develop the guideline and the policies to solve many issues on the succession of the family owned business by systemic studies. Hence, the impact of the main characteristics in the family owned business on the types of its succession was analyzed in this study focusing on five domains of Socioemtional Wealth (SEW) in view of Behavioral Agency Theory by Gomez-Mejia et al. (2007) using the data from 540 family owned small-to-medium sized businesses so as to analyze the issues on their business succession. Upon the empirical analysis results, it was confirmed that they were influenced to the selection of succession type by family succession > internal employee succession > external succession, for the variables of social contribution which were non-financial characteristics, internal employee succession > family succession > external succession for the intellectual properties, and family succession > external succession for the management participation of the family. The distinction of social contribution were influenced the most to the selection of the succession types. Financial factors, business performance, and R&D investment variables were not significantly influenced to their selection of the succession types. In case of simultaneous management, the family succession rate was high and it showed the control effect to strengthen selecting family owned business with R&D investment, social contribution, and company history variables. The behavioral agency theory used in this study was confirmed with high explanation power on the family owned business succession. The family owned business showed the tendency to maintain SEW, and non-financial factors such as accumulated know-how and social contribution based on the long term history were significantly affected to the succession in the small-to-medium sized family owned businesses, unlike general large sized listed companies. The results of this study are expected to be helpful practically for the succession of the family owned business and to suggest the guideline for the development of governmental policy.

• Economic and Environmental Geology
• /
• v.56 no.5
• /
• pp.589-601
• /
• 2023

We compare high-resolution seabed bathymetry data and seafloor backscattering data acquired, using multi-beam, between 2018 and 2021 to understand topographic changes in the coastal area of Dokdo. The study area, conducted within a 500 m × 500 m in the southern coast between the islands where Dongdo Port is located, has been greatly affected by human activities, waves and ocean currents. The depth variations exhibit between 5 - 70 m. Irregular underwater rocks are distributed in areas with a depth of 20 m or less and 30 - 40 m. As a whole, water depth ranges similar in the east-west direction and become flatter and deeper. The bathymetry contour in 2020 tends to move south as a whole compared to 2018 and 2019. The south moving of the contours in the survey area indicates that the water depth is shallower than before. Since the area where the change in the depth occurred is mainly formed of sedimentary layers, the change in the coast of Dokdo were mainly caused by the inflow of sediments, due to the influence of wind and waves caused by these typhoons (Maysak and Haishen) in 2020. In the Talus area, which developed on the shallow coast between Dongdo and Seodo, the bathymetry changed in 2020 due to erosion or sedimentation, compared to the bathymetry in 2019 and 2018. It is inferred that the changes in the seabed environment occur as the coastal area is directly affected by the typhoons. Due to the influence of the typhoons with strong southerly winds, there was a large amount of sediment inflow, and the overall tendency of the changes was to be deposited. The contours in 2021 appears to have shifted mainly northward, compared to 2020, meaning the area has eroded more than 2020. In 2020, sediments were mainly moved northward and deposited on the coast of Dokdo by the successive typhoons. On the contrary, the coast of Dokdo was eroded as these sediments moved south again in 2021. Dokdo has been largely affected by the north wind in winter, so sediments mainly move southward. But it is understood that sediments move northward when affected by strong typhoons. Such continuous coastal change monitoring and analysis results will be used as important data for longterm conservation policies in relation to topographical changes in Dokdo.

• Journal of Nutrition and Health
• /
• v.56 no.6
• /
• pp.667-682
• /
• 2023

Purpose: This study aimed to investigate the changes in health behavior, mental health, and nutritional status of Korean adolescents before and after the coronavirus disease 2019 (COVID-19) pandemic outbreak. Methods: A total of 800 adolescents (12~18 years old) who participated in the 2019-2020 Korea National Health and Nutrition Examination Survey (KNHANES) were included as study subjects and divided into four groups (204 middle school boys, 172 middle school girls, 219 high school boys, and 205 high school girls). The 2019 and 2020 KNHANES data were classified into data collected before and after the COVID-19 outbreak, respectively. Results: After the COVID-19 pandemic outbreak, middle school boys showed an increased tendency toward becoming overweight and obese, with significantly increased levels of diastolic blood pressure and insulin. While there was no major change in the subjective health status among adolescents, the high school boys showed a significantly decreased physical activity after COVID-19 outbreak. Moreover, the proportion of middle school students feeling a little stressed significantly increased after the COVID-19 outbreak. The rate of skipping breakfast significantly increased in middle school girls, but the rate of having lunch with companions significantly increased among all adolescents after the COVID-19 outbreak. However, the intake of milk, vegetables, fruits, seaweeds, and pulses significantly decreased, although the intake of sugars, beverages, and seasonings significantly decreased as well, during this period. These changes may lead to an increased proportion of adolescents with insufficient intake of nutrients, including potassium, vitamin C, and riboflavin. Conclusion: These results highlight the impact of COVID-19 on comprehensive changes in physical and mental health status, lifestyle behavior, and nutritional status in adolescents, suggesting the need for targeted prevention and intervention for physical and mental well-being during the pandemic.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.6
• /
• pp.152-161
• /
• 2023

In general, large-capacity hydrogen storage vessels, typically in the form of vertical cylindrical vessels, are constructed using steel materials. These vessels are anchored to foundation slabs that are specially designed to suit the environmental conditions. This anchoring method involves pre-installed anchors on top of the concrete foundation slab. However, it's important to note that such a design can result in concentrated stresses at the anchoring points when external forces, such as seismic events, are at play. This may lead to potential structural damage due to anchor and concrete damage. For this reason, in this study, it selected an vertical hydrogen storage vessel based on site observations and created a 3D finite element model. Artificial seismic motions made following the procedures specified in ICC-ES AC 156, as well as domestic recorded earthquakes with a magnitude greater than 5.0, were applied to analyze the structural behavior and performance of the target structures. Conducting experiments on a structure built to actual scale would be ideal, but due to practical constraints, it proved challenging to execute. Therefore, it opted for an analytical approach to assess the safety of the target structure. Regarding the structural response characteristics, the acceleration induced by seismic motion was observed to amplify by approximately ten times compared to the input seismic motions. Additionally, there was a tendency for a decrease in amplification as the response acceleration was transmitted to the point where the centre of gravity is located. For the vulnerable components, specifically the sub-system (support columns and anchorages), the stress levels were found to satisfy the allowable stress criteria. However, the concrete's tensile strength exhibited only about a 5% margin of safety compared to the allowable stress. This indicates the need for mitigation strategies in addressing these concerns. Based on the research findings presented in this paper, it is anticipated that predictable load information for the design of storage vessels required for future shaking table tests will be provided.

• Journal of Korean Elementary Science Education
• /
• v.43 no.1
• /
• pp.64-80
• /
• 2024

This study aims to investigate the characteristics of verbal interaction in science class demonstrations conducted by elementary school pre-service teachers. Specifically, the study intends to examine the use of elements of verbal interaction and the progression of these interactions. Additionally, the study intends to analyze the perception of pre-service teachers about effective questioning and feedback and to determine the correlation between the proportions of the types of questioning and feedback positively perceived by the pre-service teachers and of the types of questioning and feedback used during class demonstration. Toward this end, the study analyzed the science class demonstration videos and class evaluation sheets submitted by 38 fourth-year students at the S University of Education. The results are as follows. First, pre-service elementary school teachers generally use close-ended questions during science class demonstrations. Moreover, they predicted that students would primarily provide the correct responses and would not engage in extended interaction by providing immediate feedback for the responses of the majority of the students. Second, pre-service elementary school teachers perceived the utilization of close-ended questions and immediate feedback in science class demonstrations more favorably than they did that of open-ended questions and delayed feedback. The study observed a weak positive correlation between the positive perception of specific types of questions and feedback and the use of such types in class demonstration. The results demonstrated that pre-service elementary school pre-service teachers tend to engage in fragmented verbal interactions during science class demonstrations. They primarily use close-ended questions and immediate feedback. This tendency is seemingly related to their perception of questions and feedback. Therefore, education institutions for training pre-service teachers need to provide opportunities for reflecting on verbal interactions, which tend to involve close-ended questions and immediate feedback. Lastly, assessing the perception of pre-service teachers of questions and feedback is also necessary.

• Pediatric Infection and Vaccine
• /
• v.31 no.1
• /
• pp.75-82
• /
• 2024

Purpose: As the coronavirus disease 2019 (COVID-19) pandemic ended, the number of patients with respiratory syncytial virus (RSV) pneumonia increased during the spring/summer of 2022. This study aimed to analyze the clinical features and antibiotic usage of children hospitalized for RSV pneumonia in a recently established general hospital in Sejong city. Methods: In this retrospective review, we included inpatients of the Pediatric Department of Chungnam National University Sejong Hospital diagnosed with RSV pneumonia between March 2022 and April 2023. Patients were divided into 2 groups: with and without antibiotic treatment. Demographic data, initial presentations, and clinical courses were reviewed. Results: A total of 116 patients with RSV pneumonia were hospitalized during this period, of which 102 were analyzed, excluding 14 with underlying diseases or who did not fall within the definition of pneumonia. The median age was 17 months. Diagnoses of bacterial infections (acute otitis media and sinusitis) were documented in 9.8% of cases. Intravenous (IV) antibiotics were administered in 46% of cases. The group receiving IV antibiotics showed higher inflammatory levels (C-reactive protein; CRP), more infiltration on initial chest X-rays, and longer fever duration. There was no difference in the length of hospitalization between the groups with and without IV antibiotics. Conclusions: This study showed a tendency for the attending physician to prescribe IV antibiotics to patients with longer fever duration, pulmonary infiltrations on the initial chest X-ray, and higher CRP levels. However, given the high rate of IV antibiotic usage compared to previous studies, care should be taken in antibiotic use.

• Communications of Mathematical Education
• /
• v.38 no.2
• /
• pp.167-186
• /
• 2024

Since the 5th mathematics curriculum, the goals of mathematics education have been presented in three categories: cognitive, process, and affective goals. In the 2022 revised mathematics curriculum, the content system was also presented as knowledge-understanding, process-skill, and value-attitude. Therefore, in order to present lesson goals to students, it is necessary to present all three aspects that are the goals of mathematics education. Currently, the lesson titles presented in mathematics textbooks are directly linked to lesson goals and are the first source of information for students during class. Accordingly, this study analyzed how the three categories of lesson titles and content system presented in the 2015 revised 1st and 2nd grade mathematics textbook are connected. As a result, most lesson titles presented two of the three categories, but the reflected elements showed a tendency to focus on the categories of knowledge-understanding and process-skill. Some cases of lesson titles reflected content elements of the value-attitude category, but this showed significant differences depending on the mathematics content area. Considering the goals of mathematics lessons, it will be necessary to look at ways to present lesson titles that reflect the content elements of the value-attitude categories and also explore ways to present them in a balanced way. In particular, considering the fact that students can accurately understand the goals of the knowledge-understanding categories even without presenting them, descriptions that specifically reflect the content elements of the process-skill and value-attitude categories seem necessary. Through this, we attempted to suggest the method of presenting the lesson titles needed when developing the 2022 revised mathematics textbook and help present effective lesson goals using this.

• The korean journal of orthodontics
• /
• v.31 no.2 s.85
• /
• pp.209-223
• /
• 2001

At intrusion of upper anterior teeth in patient with periodontal defect, the use of three-piece base arch appliance for pure intrusion is required. To investigate the change of the center of resistance and of the distal traction force according to alveolar bone height at intrusion of upper anterior teeth using this appliance, three-dimensional finite element models of upper six anterior teeth, periodontal ligament and alveolar bone were constructed. At intrusion of upper anterior teeth by three-piece base arch appliance, the following conclusions were drawn to the locations of the center of resistance according to the number of teeth, the change of distal traction force for pure intrusion and the correlation to the change of vertical, horizontal location of the center of resistance according to alveolar bone loss. 1. When the axial inclination and alveolar bone height were normal, the anteroposterior locations of center of resistance of upper anterior teeth according to the number of teeth contained were as follows : 1) In 2 anterior teeth group, the center of located in the mesial 1/3 area of lateral incisor bracket. 2) In 4 anterior teeth group. the center of resistance was located in the distal 2/3 of the distance between the bracket of lateral incisor and canine. 3) In 6 anterior teeth group, the center of resistance was located in the central area of first premolar bracket .4) As the number of teeth contained in anterior teeth group increased, the center of resistance shifted to the distal side. 2. When the alveolar bone height was normal, the anteroposterior position of the point of application of the intrusive force was the same position or a bit forward position of the center of resistance at application of distal traction force for pure intrusion. 3. When intrusion force and the point of application of the intrusive force were fixed, the changes of distal traction force for pure intrusion according to alveolar bon loss were as follows :1) Regardless of the alveolar bone loss, the distal traction force of 2, 4 anterior teeth groups were lower than that of 6 anterior teeth group. 2) As the alveolar bone loss increased, the distal traction forces of each teeth group were increased. 4. The correlations of the vertical, horizontal locations of the center of resistance according to maxillary anterior teeth groups and the alveolar bone height were as follows : 1) In 2 anterior teeth group, the horizontal position displacement to the vortical position displacement of the center of resistance according to the alveolar bone loss was the largest. As the number of teeth increased, the horizontal position displacement to the vertical position displacement of the center of resistance according to the alveolar bone loss showed a tendency to decrease. 2) As the alveolar bone loss increased, the horizontal position displacement to the vertical position displacement of the center of resistance regardless of the number of teeth was increased.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.45 no.5
• /
• pp.746-756
• /
• 2016

The purpose of this study was to investigate food safety knowledge, food safety attitudes, and handling behavior in the elderly. The survey was conducted on 358 individuals over 65 years old in urban and rural areas. Data were analyzed with descriptive analysis and ${\chi}^2$ test analysis of variance using SPSS. From the results on elderly's food safety knowledge, the item 'tangerines should be washed before eating' was correctly answered by urban subjects (75.4%) than rural subjects (49.7%). 'Is it okay to cook meat left on the sink since afternoon in the evening' showed the lowest correct answer rate in both urban (23.1%) and rural (31.9%) subjects. For the item related to food keeping, 'Bacterial cells do not multiply in Samgyetang when it is kept in a refrigerator right after boiling thoroughly', 58.5% of urban and 54.6% of rural elderly answered correctly. Most elderly people showed a tendency to think that boiled foods might be safe to eat. Secondly, for food safety attitudes, urban elderly had more proper attitude regarding the item, 'Namul is very tasty only when mixed with bare hands' (disagree rate 34.9%) than rural elderly (P<0.05)'. On the other hand, rural elderly had more positive attitudes regarding the store principle "first in, first out" compared to urban elderly (P<0.001). Thirdly, regarding food safety behaviors, only 67.9% of urban and 58.7% of rural elderly responded that they washed their hands right after answering the telephone while cooking. Exactly 33.8% of urban and 39.6% of rural older people replied 'defrost meat on top of sink or table' as the defrost method for frozen foods, showing that elderly did not recognize the risk of foodborne illness during improper defrosting at room temperature.