• Journal of The Korean Association For Science Education
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• v.26 no.6
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• pp.753-764
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• 2006

The concept of blood circulation is so complex, dynamic and abstract that students have difficulty in understanding it and students' preconceptions hardly change into scientific concepts even after the lessons. The purpose of this study is to examine middle school, high school, and undergraduate students' understanding of blood circulation and to find the reason why the lack of deep understanding is displayed in students' explanations for the blood circulation. The study consists of three parts. First, the test was designed to investigate students' ideas for blood circulation as components of the structure, the function, the behavior and the mechanism. Second, the test was applied to 7th, 10th and 13th graders to investigate the students' understanding of blood circulation and categorize the types of students' blood circulation model according to their academic level. Finally, the concepts the students had little understanding of were analyzed to decide which ontological category they fell into and further to inquire the characteristics of each concept. The results showed that many students comprehend the structure and the function of blood circulation components well, and there was no significant difference in students' understanding according to the academic level. In contrast, understanding the behavior and the mechanism of circulatory components has remarkably improved in high school students and undergraduates majoring in science and engineering. Also, students' blood circulation models were classified into seven different types. High school students and undergraduates majoring in science and engineering demonstrated a significantly higher percentage on the type of double-loop-branch compared to other academic levels. In addition, it was found that the lack of deep understanding was caused by students' misconceiving the 'equilibrium' category as 'event' category.

• Journal of Practical Engineering Education
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• v.16 no.5_spc
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• pp.793-802
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• 2024

This study aimed to test a hypothetical model explaining the mediating effect of depression on the relationship between academic burnout and clinical practice stress among nursing students in the post-COVID-19 era. A cross-sectional survey was conducted with 200 senior nursing students from two universities in C province, South Korea, from December 1 to 9, 2023. Data were analyzed using descriptive statistics, Pearson's correlation, and structural equation modeling with SPSS/WIN 26.0 and AMOS 26.0. The hypothesized model explained 75.6% of the variance in clinical practice stress among nursing students. Depression did not mediate the relationship between academic burnout and clinical practice stress (β=.06, p=.160). However, both academic burnout (β=.77, p=.004) and depression (β=.23, p=.005) directly affected clinical practice stress. In the post-COVID-19 era, academic burnout significantly influences nursing students' clinical practice stress. While depression does not mediate this relationship, it directly affects clinical practice stress. These findings suggest the need for interventions focusing on reducing academic burnout through mentoring programs and stress management strategies, alongside depression management, to alleviate clinical practice stress among nursing students. Future nursing education should implement an integrated approach to manage students' academic burden and support mental health following clinical practice.

• The Korean Journal of Financial Management
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• v.24 no.4
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• pp.75-106
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• 2007

In this study, it is analyzed whether oil price plays a major role in the pricing return on Koran stock market and examined why the covariance risk between oil and return on stock is different in each industry. Firstly, this study explores whether the expected rate of return on stock is pricing due to global oil price factors as a function of risk premium by using a two-factor APT. Also, it is examined whether spill-over effects of oil price volatility affect the beta risk to oil price. Considering the asymmetry of oil price volatility, we use the GJR model. As a result, it shows that oil price is an independent pricing factor and oil price volatility transmits to stock return in only electricity and electrical equipment. Secondly, the two step-analyzing process is introduced to find why the covariance between oil price factor and stock return is different in each industry. The first step is to study whether beta risk exists in each industry by using two proxy variables like size and liquidity as control variables. The second step is to grasp the systematic relationship between the difference of liquidity and size and beta to oil price factor by using the panel-data model which can be analyzed efficiently using the cross-sectional data formed with time series. Through the analysis, we can argue that oil price factor is an independent pricing factor in only electricity and electrical equipment having the greatest market capitalization, and know that beta risk to oil price factor is a proxy of size in the other industries. According to the result of panel-data model, it is argued that the beta to oil price factor augments when market capitalization increases and this fact supports the first assertion. In conclusion, the expected rate of return of electricity and electrical equipment works as a function of risk premium to market portfolio and oil price, and the reason to make beta risk power differentiated in each industry attributes to the size.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.468-477
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• 2019

The numerical model of Boussinesq approximation, which is mainly used for evaluating the port calmness due to the irregular waves, has a limit of applicability of lattice size in ports such as marinas with narrow port openings of around 30m. The SWASH model controls the partial reflection according to the depth, porosity coefficient and structure size when applying the reflected wave incident on the structure and terrain. In this study, the partial reflection evaluation at the front of the structure according to the bottom shape and the shape of the structure are examined. In order to evaluate the reproducibility of the model due to the diffraction waves entering the term, the area of incidence at right angles and inclination of the structure is constructed and compared with the diffraction theory suggested by Goda et al. (1978). The experimental results of the sectional structure reflectances calculated as the depth mean show reflectances similar to the approximate values of the reflectances presented by Stelling and Ahrens (1981). It is considered that the reflected wave is well reproduced according to the control of the reflected wave at the boundary and the shape and topography of the structure. Compared with previous studies to examine the diffraction of the wave incident from the breakwater opening, the wave incidence angle and the shape of the diffraction wave are very similar to the theoretical values, but both oblique and rectangular incidence In the case where the direction concentration is small, the diffraction degree is underestimated in some sections with the crest ratio of 0.5 to 0.6.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.2
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• pp.17-29
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• 1997

Single-mode spectral analysis method is usually applied to a small-scale bridges with the simple geometric shape and uses only fundamental period to estimate the elastic earthquake forces and the displacements of the substructure. On the other hand, multi-mode spectral analysis method may be used instead if the possibilities of potential damage are developed when considering significance, scale, and geometric shape of briages. Since the dynamic responses of bridge can be significantly different depending on the modeling techniques for the restraint and support conditions etc, it may be misled to the unexpected results. In this study the dynamic analysis program which can model and analyze the bridge as a two- or three-dimensional framed structure is developed and verified with the results of other reliable program. Using this program together with the post processor, the designer can easily and readily obtain the reponses(moments, base shears, and displacements)of bridges necessary to design purpose. And further from the analysis results according to the variations of type, scale, and restraint and supprot conditions of bridges including sectional properties, applications of the effective and desirable seismic design are presented.

• Journal of Technology Innovation
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• v.23 no.4
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• pp.33-61
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• 2015

The global economy is rapidly changing by technological innovation and diffusion of knowledge across nations. Therefore it is still important issue to find a major variables for convergence and divergence of economic development. The studies up to present on the relationship between innovation and institution has limitations that they have dealt with this issue only in term of cross-sectional study or mathematical research models. This paper aims at analyzing the impact of innovation capabilities and institutional quality on the economic growth. Empirically this paper will explore the relationship among human capital capacity and FDI, R&D expenditures and innovation capabilities and institutional quality. This paper analyzes 64 countries, which were divided into 4 groups depending on the level of economic development. Based on the data from 1995 to 2011 and by using a panel model, we look at the structural implications of the research questions. According to our analysis, the weight of R&D and the innovation capabilities were identified as important determinants of economic growth, and FDI was significant factor for economic growth in the upper middle group countries. In case of the innovation capabilities of countries, the diffusion and openness of innovation were most meaningful variables for economic growth. Also, institutional quality has a significantly positive impact. However, in the low-level economic group, innovation capabilities and institutions have a negative impact on economic growth. This paper identifies an important policy implications that of national innovation and institutional factors should be properly invested in accordance with the level of a country's economic growth.

• The Journal of Korean Medicine
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• v.34 no.3
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• pp.13-24
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• 2013

Objectives: The aims of this study were to investigate the availability of diagnosis of Yin-deficiency in the elderly with xerostomia and factors influencing subjective oral dryness. Methods: We surveyed 50 patients recruited by the clinical trial, 'Efficacy of Yukmijihwang-tang on Xerostomia in the Elderly: A Randomized, Double-blind, Placebo-controlled, Two-center Trial'. The subjects were assessed on their subjective oral dryness using the Dry Mouth Symptom Questionnaire (DMSQ). Their salivary functions were measured by Unstimulated Salivary Flow Rate (USFR) measurements. In addition, the subjects were evaluated on their Qi-stagnation and Yin-deficiency conditions using the Qi-stagnation questionnaire and Yin-deficiency questionnaire. Results: There were statistically significant correlations between three variables (USFR, DMSQ score and Qi-stagnation score) and Yin-deficiency score. In the multiple regression analysis, the regression model was statistically significant (F = 10.273, p < .001). The factor most strongly influencing the subjective oral dryness was USFR (${\beta}$ = -0.386). Yin-deficiency had the next strongest impact on the subjective oral dryness (${\beta}$ = 0.371). Qi-stagnation affected the subjective oral dryness weakly (${\beta}$ = 0.075). In the simple regression analysis, Yin-deficiency had a statistically significant effect on each of six subscales of DMSQ (p < .01). Among the six subscales, DMSQ-1 ('Oral dryness at night or on awakening') was the most strongly influenced by Yin-deficiency. Conclusions: The results of this study show that the diagnosis of Yin-deficiency in the elderly with xerostomia was available and Yin-deficiency was an important factor influencing the subjective oral dryness. Therefore, the consideration of Yin-deficiency is significant for diagnosis and treatment in the elderly with xerostomia.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.3-12
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• 2006

The behavior of concrete structures subject to fire is complex, depending on many factors. The factors usually considered in research include the level and endurance of temperatures in concrete and reinforcing bars, the mechanical properties of the steel and concrete, moisture contents, cover thickness, existence of eccentricity, and member geometry among others. Although there are a few sophisticated numerical models which can trace the effects of these important parameters on the residual capacity of reinforced concrete columns damaged by fire, practical predictive formulas are in need for rapid yet reasonable assessment in practice. The practical formulas are developed in this study for fire-damaged normal strength reinforced concrete square columns, which can approximate the predictions of those sophisticated numerical models with ease in use. The formulas take into account the effects of exposure time to fire, concrete strength, reinforcement ratio and sectional area. The developed formulas are seen to correlate with the predictions of numerical model in a reasonable agreement. Some examples are also presented in determining the residual strength, safety and additionally needed strengths for a fire-damaged reinforced concrete column.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.551-560
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• 2014

Compare to other industrial sites, the civil construction work not only takes longer time but also has made of complicated processes, such as the integrated management, process control, and quality control until the completion. However, it is hard to take control the construction sites, since numerous issues are always emerged. The study purposes on providing the dataset to synthetically manage and monitor the civil construction site, main design, drawings, process, construction cost, and others at real-time by using the low altitude close-range aerial images, based on UAV, and the GPS surveying method for treating the three-dimensional spatial information quickly and accurately. As a result, we could provide the latest information for the quick decision-making following from planning to completion of the construction, and objective site evaluation by the high-resolution three-dimensional spatial information and drawings. Also, the present map, longitudinal map, and cross sectional view are developed to provide various datasets rapidly, such as earthwork volume table, specifications, and transition of ground level.

• 한국해양학회지
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• v.25 no.2
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• pp.62-73
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• 1990

An experimental study is performed in order to catch the characteristics of the flow field at arrested salt wedge, using a rectangular open channel. Arrested salt wedge is generally so stable that the observations are easy, but velocities and interfacial waves are measured with the aid of visualization method, by injection of fluorescent dyes. The density interface, which is defined as the zone of maximum density variation with depth, exists in about 0.5 cm below the visual interface, and vertical density profile is quite well satisfied with Homeborn model. Interfacial layer has high turbulent intensity and its thickness decreases as the overall Richardson number increases and has magnitude of roughly 17% of upper layer. Cross-sectional velocity distribution just shows the influence of a side-wall friction and in the upper layer vertical velocity profile also becomes uniformly as Reynolds number increases, but in the lower layer it shows nearly parabolic type. Supposes that we divide salt wedge into three domains, that is, river mouth, intermediate and tip zone, entertainment coefficient is small at the intermediate zone and large at the river mouth and the tip zone. River mouth or intermediate zone has comparatively stable interface and capillary wave therefore s produced and propagated downstream. On the other hand, tip zone is very unstable, cusping ripple or bursting ripple is then produced incessantly. Arrested salt wedge form is nearly linear and has no relation to densimetric Froude number and Reynolds number.