• 대한기계학회논문집A
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• 제22권2호
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• pp.278-288
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• 1998

An efficient and useful method to improve the local stress field in a displacement-formulated finite element solution has been proposed using the theory of conjugate approximations for a stress field and the Loubignac's iterative method for a displacement field. Validity of the proposed method has been tested through three test examples, to improve the stress field and displacement field in the whole domain and the local regions. As a result of analysis on the test examples, it is found that the stress field in the local regions are approximated to those in the whole domain within a few iterations which have satisfied the original finite element equilibrium equation. In addition, it is found that the local stress field are by far better approximated to the exact stress field than the displacement-based stress field with the reduction of the finite-element mesh-size.

• 한국지구과학회지
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• 제21권1호
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• pp.13-21
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• 2000

야외 학습의 많은 이점에도 불구하고, 중 고등학교에서는 야외 지질 활동이 잘 이루어지지 않고 있다. 최근에 지질 답사 지역이 많이 개발되고 있으나, 대부분 지질학적 층서에 관한 서술적 설명으로 기재되어 있어 중 고등학생들에게 적합하지 않다. 따라서 전문적인 내용보다는 지구과학 교사가 손쉽게 학생들을 데리고 야외로 나갈 수 있는 야외 학습 프로그램이 필요한 실정이다. 본 연구는 중 고등학생을 위한 야외 지질 학습장을 개발하고 이를 효과적으로 수행할 수 있는 교수 학습 전략을 제시하여 일선 지구과학 교사들에게 도움을 주고자 한다.

• 대한수학회보
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• 제52권5호
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• pp.1535-1547
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• 2015

A vector field on a Riemannian manifold (M, g) is called concircular if it satisfies ${\nabla}X^v={\mu}X$ for any vector X tangent to M, where ${\nabla}$ is the Levi-Civita connection and ${\mu}$ is a non-trivial function on M. A smooth vector field ${\xi}$ on a Riemannian manifold (M, g) is said to define a Ricci soliton if it satisfies the following Ricci soliton equation: $$\frac{1}{2}L_{\xi}g+Ric={\lambda}g$$, where $L_{\xi}g$ is the Lie-derivative of the metric tensor g with respect to ${\xi}$, Ric is the Ricci tensor of (M, g) and ${\lambda}$ is a constant. A Ricci soliton (M, g, ${\xi}$, ${\lambda}$) on a Riemannian manifold (M, g) is said to have concircular potential field if its potential field is a concircular vector field. In the first part of this paper we determine Riemannian manifolds which admit a concircular vector field. In the second part we classify Ricci solitons with concircular potential field. In the last part we prove some important properties of Ricci solitons on submanifolds of a Riemannian manifold equipped with a concircular vector field.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.174-174
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• 2001

Purpose： Dimensions of body RF coil composed of 4 rectangular loops for low field open MRI hav been optimized. The design result shows the field inhomogeneity of B1 field below 1.5 dB in the 25 cm DSV can be achieved. Method： Our low field RF coil is composed of 4 rectangular strip loops that assumed to b located at both the bottom and top sides of permanent magnet. All the loops have identica dimensions and current amplitude. First, the inductance of a loop is calculated. Second, the current distribution on the coil strip is calculated by using finite difference time doma method (FDTD). It takes as much as 4 days in FDTD simulation for low frequency RF field That's why the electrical dipole radiation method is used for simulation. With the curren distribution obtained using the FDTD simulation, for various dimensional parameters th magnetic field has been calculated by electric dipole radiation method, where the curren elements are regarded as electric dipole radiation sources. The field pattern from electri dipole radiation is almost same as that from FDTD simulation. Also, it is same as that fro the result using the Viot-Savart equation, for far tone radiation term becomes zero and th Bl field amplitude of near one radiation is the same as the B field due to static current The field homogeneity is calculated in the 25 cm BSV.

• 천문학회보
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• 제36권2호
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• pp.107.2-107.2
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• 2011

Most astrophysical systems are turbulent and magnetized. Magnetic field plays an important role in the dynamics of astrophysical system and influence all of properties of astrophysical system. Therefore, information of magnetic field is very important to understand properties of astrophysical system. One way to obtain information of magnetic field is to use rotation measure. Mean strength of the magnetic field along the line of sight can be estimated from RM/DM, where RM is rotation measure and DM is dispersion measure. For the estimation of magnetic field strength using RM/DM, the correlation between density and magnetic field. When there is no correlation between density and magnetic field the relation gives exact mean magnetic strength. But if the positive correlation, it overestimates the magnetic field strength, while if the correlation is negative, it underestimate the magnetic field strength. In general, the ICM (intracluter medium) and the ISM (interstellar medium) cases, viscosity has a value greater than magnetic diffusion. We performed compressible MHD turbulence simulations and we studied correlation between density and magnetic field in different values of viscosity and magnetic diffusion. In most cases, we found weak or negative relations between the density and magnetic fields. We discuss implication of our results.

• 미생물학회지
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• 제24권2호
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• pp.184-193
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• 1986

Interrelation between environmental influences on soil microorganisms and it's effect on disease development in ginseng (Panax ginseng C.A. Meyer) field were studied to obtain a preventive measures against the root rot of ginseng caused by soil-borne pathogens in soil in three major Korean ginseng producing areas such as Kumsan, Goesan and Poonggi. Populations of actinomycetes were relatively high in fall season from September to November. Their numbers were highly populated in healthy plot in field than replanted disease field of ginseng, whereas ratio of Trichoderma spp to actinomycetes increased in healthy plot of field indicating the higher numbers of Trichoderma spp pressented in healthy plot field. The numbers of propagules of Trichoderma spp generally increased in early summer through early fall season. Their numbers were also highly populated in the healthy plot of fields. The contents of organic matter and phosphate in healthy plot of field were somewhat high, and phophate/organic matter ratio and Mg content were high in diseased replanted field. All of the soil samples showed a weak acidic pH from 4.5 to 4.7. Soilmoisture content was increased during winter season and it did not show any significant changes curing the growing period, showing 24.6% in healthy plot in field and 19.5% in deseased plot in field respectively. Soil temperature was highest in July and August and lowest in January and February.

• 4차산업연구
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• 제3권2호
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• pp.19-26
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• 2023

Purpose - This study is to suggest a model of field education in the Assistant Nurses curriculum using edutech and to produce competent Assistant Nurses students reflecting the requirements of various medical fields. This model expects to upgrade the quality of the field education and to provide an Assistant Nurses school with standardized field education tools using edutech. Research design, data, and methodology - Throughout the review of the related thesis, most of them were studied on Assistant Nurses' job satisfaction, conflicts with other jobs in hospitals, and Assistant Nurses' job area in nursing hospitals. To study the current field education for Assistant Nurses students in hospitals, it used interviewing the heads of the hospital nursing department and reflecting on their interview results to develop the model of field education. Result - The field education model with edutech is processed with flipped class. Each area in flipped class is designed by applications and webs which is friendly to both teachers and students. Conclusion - This study presents a simple and easy process of field education using edutech. In the next study, it needs to find the precious results of comparison between students educated by the new model in field education in the Assistant Nurses' curriculum or not.

• 품질경영학회지
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• 제45권2호
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• pp.227-246
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• 2017

Purpose: This study proposes a Shiny-Sigma Methods that combines the advantages of Six Sigma method and Shainin method in order to solve field defect. Each technique has advantages and disadvantages. Methods: This study proposed Shiny-Sigma by combining Six Sigma has the logical advantage of the problem solving road map and Shiny has the merits of finding the root problem from the defective phenomenon. The Six Sigma method has the disadvantage that it is difficult to solve if the number of data is small, but the Shiny method has the advantage of finding the root cause with a small number of data. Results: As a result of applying Shiny-Sigma method to the field, it has advantages of solving the problem easily and quickly than the existing Six Sigma method. It does not require a lot of statistical knowledge, which helps field workers to use it. Based on these successes L Co. company has obtained the effect of improving the production quality by applying the Shiny-Sigma method. Conclusion: The Shiny-Sigma method proved to be suitable for the production site as a result of field application. It is suitable for field workers with low statistical knowledge and is suitable for field where data is difficult to obtain. This method is not a method to solve all the problems because there are problems that can be solved according to the field problems. We hope that this method will spread to many industrial sites and this method will have a great effect on the improvement of field production quality.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.2010-2018
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• 2003

Although continuous casting process has highly developed, there still remain many problems to be considered. Specifically, two vortex flows resulting from impingement against narrow walls make a flow field unstable in a mold, and it is directly related to internal and external defects of steel products. To cope with this instability, EMBR (Electromagnetic Brake Ruler) technique has been lately studied for the stability of molten steel flow, and it is revealed that molten steel flow in a mold can be controlled with applied magnetic field. However, it is still difficult to clarify flow pattern in an EMBR caster due to complex correlations among variables such as geometric factors, casting conditions, and the place and the intensity of charged magnetic field. In the present study, flow field in a mold is focused with different conditions of electromagnetic effect. To accurately analyze the case, three dimensional low Reynolds turbulent model and appropriate boundary conditions are chosen. To evaluate the electromagnetic effect in molten steel flow, dimensionless numbers are employed. The results show that the location and the intensity of the applied magnetic field significantly influence the flow pattern. Both impingement and internal flow pattern are changed remarkably with the change of the location of applied magnetic field. It turns out that an insufficient magnetic force yields adverse effect like channeling, and rather lowers the quality of steel product.

• 한국전기전자재료학회논문지
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• 제31권5호
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• pp.351-356
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• 2018

Commonly, a live-line alarm can be used to measure the electric field strength of a high-voltage system to calculate its current, but it is hard to detect the electric field of shielded cables or concealed structures, such as underground distribution cables. Current sensors can detect the magnetic field in a single core wire, but they cannot determine the magnetic field about a double-core wire because the currents flow in opposite directions. Therefore, it is very difficult to detect certain current problems, such as a fault current in an extension line comprised of a double line. In this paper, to ultimately develop a sensor that can detect the current regardless of line conditions, we used a simulation to determine the concentration of the magnetic field dependent on the distribution of the external magnetic field and the path of each line's core.