• Structural Engineering and Mechanics
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• v.76 no.1
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• pp.27-56
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• 2020

In this paper, the deflection and buckling analyses of porous nano-composite piezoelectric plate reinforced by carbon nanotube (CNT) are studied. The equations of equilibrium using energy method are derived from principle of minimum total potential energy. In the research, the non-local strain gradient theory is employed to consider size dependent effect for porous nanocomposite piezoelectric plate. The effects of material length scale parameter, Eringen's nonlocal parameter, porosity coefficient and aspect ratio on the deflection and critical buckling load are investigated. The results indicate that the effect of porosity coefficient on the increase of the deflection and critical buckling load is greatly higher than the other parameters effect, and size effect including nonlocal parameter and the material length scale parameter have a lower effect on the deflection increase with respect to the porosity coefficient, respectively and vice versa for critical buckling load. Porous nanocomposites are used in various engineering fields such as aerospace, medical industries and water refinery.

• Computers and Concrete
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• v.24 no.6
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• pp.499-511
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• 2019

In this paper, wave propagation of double-bonded Cooper-Naghdi micro sandwich cylindrical shells with porous core and carbon nanotube reinforced composite (CNTRC) face sheets are investigated subjected to multi-physical loadings with temperature dependent material properties. The governing equations of motion are derived by Hamilton's principle. Then, the influences of various parameters such as wave number, CNT volume fraction, temperature change, Skempton coefficient, material length scale parameter, porosity coefficient on the phase velocity of double-bonded micro sandwich shell are taken into account. It is seen that by increasing of Skempton coefficient, the phase velocity decreases for higher wave number and the results become approximately the constant. Also, by increasing of the material length scale parameter, the cut of frequency increases, because the stiffness of micro structure increases. The obtained results for this article can be used to detect, locate and quantify crack.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.1-12
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• 2019

One of proposed Accident Tolerant Fuel (ATF) concept is fully ceramic micro-encapsulated fuel (FCMF). FCMF using uranium mononitride (UN) has better safety aspects than $UO_2$ pellet fuel although it might not have a better neutronic performance due to the presence of matrix and high neutron-induced interaction of $^{14}N$. Before implementing UN-FCMF technology in Small-PWR, further research must be taken place to make sure the proposed design of fuel assembly has inherent safety features and maintain the fuel performance. This study focusses on the neutronic analysis of UN-FCMF based fuel assembly using Serpent and SCALE codes. It is shown in the proposed fuel assembly design has inherent safety features with respect to the fuel temperature reactivity coefficient, void reactivity coefficient, and moderator temperature reactivity coefficient. It is noted that the use of FCMF leads to a lower ratio of burnup to $^{235}U$ enrichment ratio compared to the $UO_2/Zr$ fuel.

• Journal of Korean Academy of Nursing
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• v.35 no.1
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• pp.113-124
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• 2005

Purpose: The purpose of this study was to develop a health conservation scale with high validity and reliability for institutionalized elderly. Method: The process of development of this scale was as follows. A conceptual framework composed of 4 phases of health conservation of institutionalized elderly was identified based on the literature review with elderlies and discussions with experts in health conservation. A total of 75 items, on a 4-point scale were developed. Through reliability testing and factor analysis, 57 preliminary items were selected. By means of internal consistency of the 57 items, 18 items whose inner-items correlation coefficient was below .40 were deleted. Through factor analysis, 2 items whose factor loading was below .40 were deleted. Finally 37 items remained. To verity the 37 items, factor analysis, reliability testing, and correlation was done. Data were collected from 207 institutionalized elderly subjects in Daegu, Kyungpook, Busan, and KyungNam Province from August. 2003 to February. 2004. Result: In the result of factor analysis of the 37 items, 4 factors were extracted. These factors were labeled as ‘personal integrity’, ‘conservation of energy', ‘structural integrity’, and ‘social integrity'. These factors included 4 phases of health conservation. Cronbach's Alpha of 37 the items was .9424 and the correlation coefficient of HPLP was .723. Conclusion: The researchers recommend the following: An explorative study on the variables related to health conservation is needed for criterion validity of this scale. Studies on health conservation of different age groups, and subjects are needed for verification.

• Journal of Korean Academy of Nursing
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• v.33 no.3
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• pp.414-424
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• 2003

Purpose: The purpose of this study was to develop elderly meaning in life scale with high validity and reliability. Method: The process of development of this scale were as follows. A conceptual framework composed of 4 phases of meaning in life of elderly was identified based on the literature review and interviews with elderlies and discussion with experts in meaning in life. Total 62 items, 4-points scale were developed. Through reliability testing, factor analysis, 40 preliminary items were selected. By means of internal consistency of 40 items, 2 items whose inner-items correlation coefficient was below .30 were deleted. Through factor analysis 1 item whose factor loading was below .30 was deleted. Finally 37 items were remained. To verify 37 items, factor analysis, reliability testing, LISEREL were done. Data were collected from 320 elderly subjects in Busan-KyungNam and Jeonla Province from May to June in 2002. SPSS WIN. 10.0 Program was used. Result: The result of factor analysis of 37 items, 8 factors were extracted. These factors were labeled as ‘self- awareness and self-acceptance’, ‘contentedness with life’, ‘purpose in life’, ‘love in family’, ‘role awareness’, ‘futuristic aspiration’, ‘commitment’, and ‘experience of love’. These factors included 4 phases of the meaning in life. Cronbach's Alpha of 37 items was .908 and correlation coefficient of PIL was .75. Conclusion: The researchers recommend the follows: The explorative study on the variables related to meaning in life are needed for criterion validity of this scale. The studies on meaning in life of different age groups, subjects are needed for reverification.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.33-40
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• 2024

The concentration and diffusion coefficient of oxide ion vacancies in the oxide scale formed on Fe-22Cr-0.5Mn ferritic stainless steel with and without molybdenum (Mo) was measured at 800℃ by the electrochemical polarization method. After pre-oxidation for 100 h in ambient air at 800 ℃, the oxide scale on one side was completely removed with sandpaper. A YSZ plate was placed on the side where the oxide scale remained. Platinum (Pt) meshes were attached on the top of the YSZ plate and the side where the oxide scale was removed. Changes in electrical current were measured after applying an electrical potential through Pt wires welded to the Pt meshes. The results were interpreted by solving the diffusion equation. The diffusion coefficient and concentration of oxide ion vacancy decreased by 30% and 70% in the specimen with Mo, respectively, compared to the specimen without Mo. The oxide ion vacancy concentration of chromia decreased due to the addition of Mo.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.639-647
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• 2013

This paper is a methodological research aimed at developing a mental disorder recovery scale (MDRS) and testing its validity and reliability. After three sessions of factor analysis, a total of three factors using an Eigen value of 1.0 or more were drawn. The explanatory power was found to be 58.1%. All the items met the criteria for communality and factor loading with no item removed, and, ultimately, 25 items were selected. Criterion-related validity test showed that Pearson's correlation coefficient was significant at .71 (p<.01) with significant correlation with each factor (p<.01). The reliability test showed that Cronbach's ${\alpha}$ coefficient was .95 and that Cronbach's ${\alpha}$ coefficient for each factor ranged from .87 to .93. MDRS, which was developed in this study and possessing 3 factors and 25 items, had both its validity and reliability confirmed; therefore, the developed scale would be useful to evaluate the recovery of individuals with mental disorder.

• KSTLE International Journal
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• v.5 no.2
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• pp.37-43
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• 2004

Abstract : Nano/micro-scale friction properties were investigated on Si (100) and three self-assembled monolayers (SAMs) (PFOTC, DMDM, DPDM) coated on Si-wafer by chemical vapor deposition technique. Experiments were conducted at ambient temperature(24$pm$1$circ$C) and humidity(45$pm$5%). Friction at nano-scale was measured using Atomic Force Microscopy (AFM) in the range of 0-40nN normal loads. In both Si-wafer and SAMs, friction increased linearly as a function of applied normal load. Results showed that friction was affected by the inherent adhesion in Ssi-wafer, and in the case of SAMs the physical/chemical structures had a major influence. Coefficient of friction of these test samples at the micro-scale was also energies. In order to study the effect of contact area on coefficient of friction at the micro-scale, friction was measured for Si-wafer and DPDM against Soda Lime balls (Duke Scientiffic Corporation) of different radii (0.25 mm, 0.5 mm and 1 mm) at different applied normal loads (1500, 3000 and 4800 mN). Results showed that Si-wafer had higher coefficient of friction than DPDM. Further, unlike that in the case of DPDM, friction in Si-wafer was severely influenced by its wear. SEM evidences showed that solid-solid adhesion was the wear mechanism in Si-wafer.

• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1445-1453
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• 2013

The scale-up criterion of constant oxygen mass transfer coefficient ($k_La$) was applied for the production of itaconic acid (IA) in a 50 L pilot-scale fermentor by the fungal cells of Aspergillus terreus. Various operating conditions were examined to collect as many $k_La$ data as possible by adjusting the stirring speed and aeration rate in both 5 L and 50 L fermentor systems. In the fermentations performed with the 5 L fermentor, the highest IA production was obtained under the operating conditions of 200 rpm and 1.5 vvm. Accordingly, we intended to find out parallel agitation and aeration rates in the 50 L fermentor system, under which the $k_La$ value measured was almost identical to that ($0.02sec^{-1}$) of the 5 L system. The conditions of 180 rpm and 0.5 vvm in the 50 L system turned out to be optimal for providing almost the same volumetric amount of dissolved oxygen (DO) into the fermentor, without causing shear damage to the producing cells due to excessive agitation. Practically identical fermentation physiologies were observed in both fermentations performed under those respective operating conditions, as demonstrated by nearly the same values of volumetric ($Q_p$) and specific ($q_p$) IA production rates, IA production yield ($Y_{p/s}$), and specific growth rate (${\mu}$). Specifically, the negligible difference of the specific growth rate (${\mu}$) between the two cultures (i.e., $0.029h^{-1}$ vs. $0.031h^{-1}$) was notable, considering the fact that ${\mu}$ normally has a significant influence on $q_p$ in the biosynthesis of secondary metabolites such as itaconic acid.

• Journal of the Korean Home Economics Association
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• v.36 no.6
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• pp.95-108
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• 1998

This study is the second study which was aimed to validate the Infant/ Toddler Environment Rating Scale(ITERS). The test-retest reliability included 10 infant/toddler classes among 30 national/public and private child care centers in Inchon city which had been observed in the first validation study. The Spearman's correlation coefficient for test-retest reliability was ranged from .52 to .84. In addition, two raters observed 10 family day care centers in Inchon city, where two observers independently rated each centers on the ITERS during a single visit. The Spearman's correlation coefficient for interrater reliability was ranged from.72 to .99 For the second measure of content validity, experts who were working in day care centers and who were graduate students, lecturers, or professors majoring child studies rated the appropriateness of each ITERS items for the provision of high-quality programs for infants and toddlers, using a 1(low) to 5(high) scale. The mean rating was ranged from 2.52 to 4.52. In sum, when the rating scores were analyzed by the type of child care centers, national/public child care centers have better quality than private or family child care centers.