• 한국세라믹학회지
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• 제46권2호
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• pp.123-130
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• 2009

To understand the formation of core-shell structure in $BaTiO_3$ (BT) grains in multilayer ceramic capacitors, specimens were prepared with BT powders mixed with Y and Mg, and their microstructures were investigated with scanning electron microscopy, x-ray diffractometry, and transmission electron microscopy. Microstructural investigation showed that Y dissolved easily in BT lattice to a certain depth inside of the grain, whereas Mg tended to stay at grain boundaries rather than become incorporated into BT. It was considered that in case of Y and Mg addition in a proper ratio, Y could play a dominant role in the formation of shell leading to a slight dissolution of Mg in the shell. Next, the effects of ball-milling conditions on the core-shell formation were studied. As the ball-milling time increased, the milled powders did not show a significant change in size distribution but rather an increase of residual strain, which was attributed to the milling damage. The increase in milling damage facilitated the shell formation, leading to the increased shell portion in the core-shell grain.

• 임상간호연구
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• 제23권1호
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• pp.40-53
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• 2017

Purpose: The purpose of this study was to identify core competencies for new nurses and valuate the appropriateness and capability of core competencies. Methods: Mixed method was applied for the study. Qualitative data were obtained from preceptor and nurse manager utilizing an open-ended survey question and qualitative data analysis was conducted. The quantitative data were collected from 238 nurses (79 new nurses, 78 preceptors, 81 nurse managers) and descriptive statistics, ANOVA, $x^2$ tests were applied. Results: Three themes (20 contents) were identified as core competencies: competency as an employee, competency to perform nursing care for patient, competency to maintain nursing expertise. New nurses recognized themselves as having higher competency as an employee and to perform nursing care for patient when compared to nurse managers. Conclusion: The findings identified core competencies for new nurses need to be reflected to developing human resource management strategies for hiring new nurses.

• Nuclear Engineering and Technology
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• 제52권4호
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• pp.674-680
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• 2020

We used MCNP6 computer code to model HTR-10 core reactor. We used two types of fuel; UO₂ and (Th+Pu)O₂ mixture. We determined the critical height at which the reactor approached criticality in both two cases. The neutronic and burnup parameters were investigated. The results indicated that the core fueled with mixed (Th+Pu)O₂, achieved about 24% higher fuel cycle length than the UO₂ case. It also enhanced safeguard security by burning Pu isotopes. The results were compared with previously published papers and good agreements were found.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.40-45
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• 1996

A new concept of equivalent homogenization is proposed. The concept employs new set of homogenized parameters: homogenized cross sections (XS) and interface matrix (IM), which relates partial currents at the celt interfaces. The idea of interface matrix generalizes the idea of discontinuity factors (DFs), proposed and developed by K.Koebke and K.Smith. The method of K.Smith can be simulated within framework of new method, while the new method approximates heterogeneous cell better in case of the steep flux gradients at the cell interfaces. The attractive shapes of new concept are: improved accuracy, simplicity of incorporation in the existing codes, equal numerical expenses in comparison to the K.Smith's approach. The new concept is useful for: (a) explicit reflector/baffle simulation; (b) control blades simulation; (c) mixed UO2/MOX core simulation, The offered model has been incorporated in the finite difference code and in the nodal code PANBOX. The numerical results show good accuracy of core calculations and insensitivity of homogenized parameters with respect to in- core conditions.

• Steel and Composite Structures
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• 제1권2호
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• pp.159-170
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• 2001

The Millennium Tower is situated to the north of the center of Vienna. With a height of 202 m it is the highest building in Austria. Realization was improved by new methods. The tower is a typical example of mixed building technology, combining composite frames with a concrete core. Special attention has been paid to the moment connections between the slim floors and the column tubes resulting in a drastically reduced construction time and thin slabs. The semi-continuity has been considered in the design at ultimate and serviceability limit states.

• 한국멀티미디어학회논문지
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• 제11권12호
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• pp.1716-1721
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• 2008

Currently, Wireless Networks have some nice characteristics such as multi-hop, multi-channel, multi-radio, etc but these kinds of resources are not fully used. The most difficulty to solve this issue is to solve mixed integer optimization. This paper proposes a method to solve a class of mixed integer optimization for wireless networks by using AMPL modeling language with CPLEX solver. The result of method is scheduling and congestion control in multi-channel multi-radio wireless networks.

• 한국세라믹학회지
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• 제40권2호
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• pp.146-152
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• 2003

지구온난화의 주요 원인인 $CO_2$를 분해시키기 위하여 Ni-Zn 페라이트와 Mn-Zn 페라이트 코어 제조시 대량으로 배출되는 페라이트 폐기물을 이용하였다. 폐기물 페라이트와 페라이트 코어 완제품인 Ni-Zn 페라이트와 Mn-Zn 페라이트는 5% $H_2$/Ar과의 환원반응에서 14~16wt%가 환원되었다. 환원된 페라이트를 이용한 $CO_2$분해 반응에서는 세 종류의 페라이트 모두 약 11wt%에 해당하는 $CO_2$를 분해하였다. 이 반응에서 $CO_2$는 환원된 페라이트 중 Fe와 FeO치 산화에 의해 분해되었으며. 폐기물 페라이트의 경우 $CO_2$분해 반응 후 스피넬 결정상을 형성하였다. 대량으로 버려지는 폐기물 페라이트를 이용하여 저비용으로 $CO_2$분해가 가능한 폐기물 활용기술을 개발하였다.

• Journal of Magnetics
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• 제21권2호
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• pp.192-196
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• 2016

The Fe-Si-B-Nb-Cu alloys containing Ca and Al were rapidly solidified to thin ribbons by melt-spinning. The ribbons were ball-milled to make powders, and then mixed with 1 wt.% water glass and 1.5 wt.% lubricant. The mixed powders were burn-off, and then compacted to form toroidal-shaped cores, which were heat treated to crystallize the nano-grain structure and to remove residual stress of material. The characteristics of the powder cores were analyzed using a differential scanning calorimetry (DSC) and a B-H meter. The microstructures were observed using transmission electron microscope (TEM). The optimized soft magnetic properties (${\mu}_i$ and $P_{cv}$) of the powder cores were obtained from the Ca and Al containing alloys after annealing at $530^{\circ}C$ for 1 h. The core loss of Fe-Si-B-Nb-Cu-based powder cores was reduced by the addition of Ca element, and the initial permeability increased due to the addition of Al element.

• 한국운동역학회지
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• 제33권4호
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• pp.155-163
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• 2023

Objective: The purpose of this study is to identify the difference in the quality of muscle contraction and kick movements according to the presence or absence of back pain in body kick movements of mixed martial arts athletes. Method: In this study, four athletes (32.75 ± 4.79 yrs, 172.50 ± 5.20 cm, 77.73 ± 13.28 kg) who have suffered chronic back pain for more than three months and scored 12 points in the Korean version of ODI. Four painless athletes (33.50 ± 4.04 yrs, 174.25 ± 3.10 cm, 83.50 ± 10.21 kg) participated. Results: During the body kick operation, the pain group had significantly higher muscle activity in the right Transversus abdominis and right Rectus femoris compared to the normal group (p<.05). In the rectus abdominis, the muscle activity was significantly lower than that of the normal group (p<.05). Also, the pain group has a higher toe speed than the normal group Significantly slow (p<.05), there was a delay in contraction of the Transversus abdominis. Conclusion: The results of this study suggest that chronic pain in the lumbar spine degrades the core's function, resulting in inefficient coordination such as Transversus abdominis contraction delay and Transversus abdominis and Rectus femoris excessive activation to compensate for it.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.106-106
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• 2017

The soybean [Glycine max (L.) Merr.] is one of the most important crop resources worldwide as food and forage. It is also important and valuable that to hold crop resources to have high genetic diversities. Recently, a core collection has been constructed in many plants to preserve the genetic resources of various plants. A core collection is small population to represent the genetic diversity of the total collection, and is of strategic importance as they allow the use of a small part of a germplasm collection that is representative of the total collection. Here, we developed the core collection consisting of 816 accessions by using approximately 180,000 (180K) single nucleotide polymorphisms (SNPs) developed in previous study. In addition, we performed genetic diversity and population structure analysis to construct the core collection from entire 4,392 collections. there were excluded sample call rates less than 93% and duplicated samples more than 99.9% according to genotype analysis using 180K SNPs from entire collections. Furthermore, we were also excluded natural hybrid resources which Glycine max and Glycine soja are mixed in half through population structure analysis. As a result, we are constructed the core collection of genetic diversity that reflects 99% of the entire collections, including 430 cultivated soybeans (Glycine max) and 386 wild soybeans (Glycine soja). The core collection developed in this study should be to provide useful materials for both soybean breeding programs and genome-wide association studies.