• Korean Journal of Organic Agriculture
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• v.11 no.3
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• pp.21-35
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• 2003

Environmental-friendly agriculture(EFA) has been mainly developed at many areas which have factors of natural, social cultural and economic characteristics. These rural areas can be developed into environmental-friendly space to preserve ecosystem, natural and cultural scenery, and environmental resources. The plan for developing a regional agriculture has to get central operating bodies, producers' organizations, a homogeneous district for farming, and so on. This case study is focused on development directions and situations of the EFA of Kosam area in Anseong. Kosam cooperatives is a central managing body to produce and sell rice by duck-farming method, and to develop rural area. This cooperatives is one of the leading those that have developed the regional agriculture in Korea. Kosam area is at a disadvantage of natural-geographical conditions and farming size. Kosam cooperatives has been trying to overcome these agricultural weaknesses by introducing duck-farming method. They have got many excellent results through developing EFA as a regional agriculture. Kosam area will be a good place for green tourism if they can actualize the combination model of three demand factors (natural and agricultural scenic view, natural-friendly recreation and safe food) for green tourism in the near future.

• Child Health Nursing Research
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• v.29 no.1
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• pp.37-50
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• 2023

Purpose: This study aimed to validate the Child Healthy Lifestyle Profile as an instrument for screening healthy behaviors in school-aged children in South Korea. Methods: Self-reported questionnaires were administered to 454 students, comprising elementary-school students (n=221) and child cancer survivors (n=233). Reliability and validity were assessed using Cronbach's α, exploratory factor analysis (EFA), and confirmatory factor analysis (CFA). Results: Cronbach's α, as a reliability test, was 0.87. Varimax rotation yielded nine factors with eigenvalues greater than 1 in the EFA, which explained 61.0% of the total variance. In the CFA, both convergent and discriminant validities were acceptable. Therefore, the Child Healthy Lifestyle Profile was validated as an assessment tool for Korean school-aged children. Conclusion: Based on the results of this study, the Child Healthy Lifestyle Profile was identified as a reliable and valid instrument for assessing healthy lifestyles in elementary-school children in South Korea.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.133-140
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• 2023

Soil erosion can cause scouring and failures of underwater structures, therefore, various soil improvement techniques are used to increase the soil erosion resistance. The microbially induced calcium carbonate precipitation (MICP) method is proposed to increase the erosion resistance, however, there are only limited experimental and numerical studies on the use of MICP treatment for improvement of surface erosion resistance. Therefore, this study investigates the improvement in surface erosion resistance of sands by MICP through laboratory experiments and numerical modeling. The surface erosion behaviors of coarse sands with various calcium carbonate contents were first investigated via the erosion function apparatus (EFA). The test results showed that MICP treatment increased the overall erosion resistance, and the contribution of the precipitated calcium carbonate to the erosion resistance and critical shear stress was quantified in relation to the calcium carbonate contents. Further, these surface erosion processes occurring in the EFA test were simulated through the coupled computational fluid dynamics (CFD) and discrete element method (DEM) with the cohesion bonding model to reflect the mineral precipitation effect. The simulation results were compared with the experimental results, and the developed CFD-DEM model with the cohesion bonding model well predicted the critical shear stress of MICP-treated sand. This work demonstrates that the MICP treatment is effective in improving soil erosion resistance, and the coupled CFD-DEM with a bonding model is a useful and promising tool to analyze the soil erosion behavior for MICP-treated sand at a particle scale.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.533-537
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• 2004

The erodibility of soil is an important factor to scour, especially in fine-grained soils. In this study, the erosion characteristics of kaolinite are quantified through the scour rate tests using the Erosion Function Apparatus called EFA. The basic soil property tests are also performed. The kaolinite samples are prepared by mixing with distilled water and formed to the designed maximum consolidation pressure of 60, 110, 160, 240, 360kPa, respectively. The results of the scour rate tests are presented in a format of a plot showing the relationship between erosion rates and shear stresses. Erosion properties of kaolinite showed a striking contrast according to the maximum consolidation pressure, and a correlation was established between the erosion properties of kaolinite and the soil properties; water content, undrained shear strength, dry density.

• Journal of Navigation and Port Research
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• v.32 no.9
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• pp.723-727
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• 2008

Sensing performances of evanescent field absorption (EFA) hetero-core fiber sensor has been presented based on EFA by changing the length and the core diameter of the single mode fiber. Experimental results have demonstrated a good feature in their relationship between the length and the core diameter of the single mode fiber. The sensor consists of 2 fiber optics which have the same cladding diameter of $125{\mu}m$ However one fiber optic used is single mode and has varying core diameter ranging from 3.3 to $5.6{\mu}m$. The other fiber is multimode type and has a thicker fixed core diameter of $62.5{\mu}m$. The 2 fiber optics are thermally spliced together. Experiments conducted to measure the resonance wavelength were carried out over a range of refractive index, to find the optimum sensing length Experiments show that core diameter of the single mode fiber and sensing length offects the linearity and sensitivity.

• Defense and Technology
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• no.11 s.153
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• pp.38-46
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• 1991

국제공동개발은 국수주의(내쇼날리즘), 기술이전, 기업간의 경쟁, 각국 조직기구의 서로 다른점등 4대 장애를 비롯하여 여러 어려움이 뒤따른다. 실제적으로 구체적인 공동개발 추진단계에 이르면, 매우 많은 난제들이 발생하게 된다. 대표적인 예가 EFA계획이다. 또한 전혀 다른 임무를 요구하면서도 그것을 1개 기종에 실현하고자 노력하는 경우도 있다. 이는 현대 첨단장비의 개발과 조달에는 많은 자금이 소요되기 때문이다

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.307-314
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• 2016

Energy flow analysis(EFA) is a representative method that can predict the statistical energetics of structures at high frequencies. Generally, as the frequency increases, the shear distortion and rotatory inertia effects in the out-of-plane motion of beams or plates become important. Therefore, to predict the out-of-plane energetics of coupled structures in the high frequency range, the energy flow analyses of Timoshenko beam and Mindlin plate are required. Unlike the energy flow model of Kirchhoff plate, the energy flow model of Mindlin plate is composed of three kinds of energy governing equations(out-of-plane shear wave, bending dominant flexural wave, and shear dominant flexural wave). This paper performed the energy flow finite element analysis(EFFEA) of coplanar coupled Mindlin plates. For EFFEA of coplanar coupled Mindlin plates, the energy flow finite element formulation of out-of-plane energetics in the Mindlin plate was performed. The general EFFEA program was implemented by MATLAB® language. For the verification of EFFEA of Mindlin plate, the various numerical applications were done successfully.

• Research in Community and Public Health Nursing
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• v.19 no.2
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• pp.247-259
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• 2008

Purpose: This study was conducted to develop a teacher-efficacy scale which is adequate for heath education teachers. Method: A preliminary questionnaire was made based on the hypothetical factors. A total of 364 health education teachers answered to the preliminary test, and the potential factors of teacher-efficacy were checked out by exploratory factor analysis (EFA). In the main test 378 health education teachers answered, the factor structure was drawn by EFA, and confirmatory factor analysis (CFA) was conducted to test and the fitness of the factor model. Results: Through the preliminary test, 5 potential factors were found, which were instruction, health-service, administrative task, interpersonal relationship, and community connection. Also, 48 items were reduced to 31 items. Through the main test, from the 34 items were extracted 4 factors with 24 items, And then teacher-efficacy scale was developed, which included the subscales of instruction efficacy, health-service efficacy, task-interpersonal efficacy, and community connection efficacy. Conclusion: Different from that for other subject teachers, the factor structure for health teachers had 4 factors with 24 items. The scale developed in this study is consistent with health teachers' work areas, and for this reason, has significance as a adequate and valid scale to measure teacher-efficacy of health education teachers.

• Journal of Distribution Science
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• v.19 no.10
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• pp.17-22
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• 2021

Purpose: Covid-19 has caused an unprecedented situation for the tourism industry with slumping demand during the outbreak and many uncertainties about tourist behavior in the post-pandemic. This study is aimed to discover the distribution in the behavior of tourists in Vietnam, whose government has taken serious and early actions towards the health crisis and among the earliest to reopen the economy. Research design, data, and methodology: We adopted a mixed-method approach - combining qualitative interviews with quantitative research using a questionnaire survey. Through the form of the online survey through social networking channels: Facebook, Gmail. The study received 261 valid responses for analysis. Multivariate analysis techniques were used: descriptive statistics, exploratory factor analysis (EFA). Results: From the data and result of EFA, the result showed that the distribution of tourist behavior could be grouped into four main factors, including (1) the general impacts, (2) travel-related behaviors; (3) attitudes and preferences regarding modes of tours and destinations; (4) awareness of safety and hygiene. Conclusions: These results highlighted the importance of the theory of perceived risks in explaining the travelers' prudent decisions. In addition, this study provides practical implications for policymakers and various stakeholders of Vietnam's tourism industry in formulating the recovery strategy.

• Geomechanics and Engineering
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• v.25 no.1
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• pp.49-58
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• 2021

The resistance of soil to the tractive force of flowing water is one of the essential parameters for the stability of the soil when directly exposed to the movement of water such as in rivers and ocean beds. Biopolymers, which are new to sustainable geotechnical engineering practices, are known to enhance the mechanical properties of soil. This study addresses the surface erosion resistance of river-sand treated with several biopolymers that originated from micro-organisms, plants, and dairy products. We used a state-of-the-art erosion function apparatus with P-wave reflection monitoring. Experimental results have shown that biopolymers significantly improve the erosion resistance of soil surfaces. Specifically, the critical shear stress (i.e., the minimum shear stress needed to detach individual soil grains) of biopolymer-treated soils increased by 2 to 500 times. The erodibility coefficient (i.e., the rate of increase in erodibility as the shear stress increases) decreased following biopolymer treatment from 1 × 10-2 to 1 × 10-6 times compared to that of untreated river-sands. The scour prediction calculated using the SRICOS-EFA program has shown that a height of 14 m of an untreated surface is eroded during the ten years flow of the Nakdong River, while biopolymer treatment reduced this height to less than 2.5 m. The result of this study has demonstrated the possibility of cross-linked biopolymers for river-bed stabilization agents.