• Title/Summary/Keyword: Stress Fields

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STUDY ON EFFECTIVENESS OF NURSING PROFESSORS BY PERCEPTUAL ORIENTATION SCALE (지각향성검사에 의한 전문직 간호 교수들의 직업효율성에 관한 일 연구)

  • 김윤희
    • Journal of Korean Academy of Nursing
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    • v.3 no.3
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    • pp.27-35
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    • 1973
  • This thesis intends to make a study on the effectiveness of Nursing Professors through perceptual psychological approach. Purpose of the Study Researches have been made relating teacher′s effectiveness measurement. However, they share a common defect that they have been done on the basis of superficial aspects of the problems aspects that can bi measured by general objective survey only, but this study is designed "to understand his behavior in terms of a human behaving and of a self as an instrument"-principle, based upon the Perceptual Psychology which puts more stress on the inner perception than on the external one. Method of the Study This thesis is based chiefly on the two sources : "Perceptual Orientation Scale"(Chunghoon Choy, 1971) which has been standardized on the basis of perceptual psychology and the question acres made by the researcher of this thesis and given to the 34 Nursing Professors in seoul and other country. Result of the Study The method of data operation by Pearson "r" asserts that there were distinct deep relation Between Perceptual orientation and fellow′s estimate, while a little relation among the estimate of a-administration, educational backgrounds and occupations but no relations the status of experiences. It can be concluded that the estimates between fellows working at "the same fields" have kept deep relations together on perceptual orientation which resulted from finding out a useful method to measure occupational effectiveness according to the perceptual field. Conclusion of the Study The personnel administration has been managed according to external flatus and not positive operation: on the other hand, this study holds, It shall be operated in accordance with the estimates by fellow, the "Preceptual Orientation Scale" for more positive ability. The study requires the following researches on the devoted professional occupations, such as medical doctors, teachers, nurses, etc. for the purpose of increasing their occupational effectiveness more scientifically.

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TEM Investigations of Structures and Phase Transitions in Tridymite (투과전자현미경을 이용한 Tridymite의 구조 및 상전이 연구)

  • 김윤중
    • Journal of the Mineralogical Society of Korea
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    • v.15 no.1
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    • pp.44-58
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    • 2002
  • A new polymorph of tridymite, an incommensurately modulated phase (IC phase), has been identified. While the symmetry of the IC lattice is same as that of the Ll phase, the geometry of the IC lattice structure is same as the basis of the L3 structure with a different modulation (modulation vector q=0.22 $c*_{H}$;$\lambda$ 37 ). On the other hand, the characteristic curved diffuse diffration observed from the Ll atoms could occur even at room phase suggests that the dynamic disordering of atoms, especially oxygen atoms could occur even at room temperature. The phase transition of Ll to L3 by grinding is gradual but very conspicuous: LllongrightarrowL1+IClongrightarrowIC+L3longrightarrowL3. However, it is revealed that real transition processes of individual grains are directly related to the local stress fields and preexisting microstructures.

PERFORMANCE ASSESSMENT OF THE RANS TURBULENCE MODELS IN PREDICTION OF AERODYNAMIC NOISE FOR AIR-CONDITIONER INDOOR UNIT (에어컨 실내기의 공력소음 예측을 위한 RANS 난류모델의 성능 평가)

  • Min, Y.H.;Kang, S.;Hur, N.;Lee, C.;Park, J.
    • Journal of computational fluids engineering
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    • v.17 no.4
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    • pp.81-86
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    • 2012
  • The objective of the present study is to investigate the effects of various turbulence models on the aerodynamic noise of an air-conditioner (AC) indoor unit. The results from URANS (unsteady Reynolds-averaged Navier-Stokes) simulations with the standard k-$\varepsilon$, k-$\omega$ shear stress transport (SST) and Spalart-Allmaras (S-A) turbulence models were analyzed and compared with the noise data from the experiments. The frequency spectra of the far-field acoustic pressure were computed using the Farrasat equation derived from the Ffowcs Williams-Hawkings (FW-H) equation based on the acoustic analogy model. Two fixed fan casings and the rotating cross-flow fan were used as the source surfaces of the dipole noise in the Farrasat equation. The result with the standard k-$\epsilon$ model showed a much better agreement with the experimental data compared to the k-w SST and S-A models. The differences in the pressure spectra from the different turbulence models were discussed based on the instantaneous vorticity fields. It was found that the over-estimated power spectra with the k-w SST and S-A models are related to the emphasized small-scale vortices produced with these models.

Simulation and Design of High-Speed Hydraulic Velocity Generator in Shock Test Machine (충격시험장치 고속유압 속도발생기 해석 및 설계)

  • Kim, Tae Hyeong;Shul, Chang Won;Kim, Yoon Jae;Yang, Myung Seog;Lee, Gyu Sub
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.6
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    • pp.663-668
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    • 2014
  • Mechanical and electrical devices in various forms are used in many different fields. These can be exposed to external environmental factors such as shock. Therefore, a shock test machine is commonly used to test these devices and evaluate their shock resistance. In this test, the break-down or permanent deformation and malfunction of inner parts due to a high stress or acceleration can be evaluated. As part of a shock test machine, a velocity generator is needed to create shocks between objects. In this study, a hydraulic velocity generator was conceptually designed and an AMESim model was developed to simulate the velocity under different conditions. Simulation results using this model were compared with the test results from a reduced-size velocity generator, and we designed a velocity generator that fits the target payload and velocity using the simulation results.

Application of a New NDI Method using Magneto-Optical Film for Inspection of Micro-Cracks (미소균열 탐상을 위한 자기광학소자를 이용한 비파괴탐상법의 제안과 적용)

  • Lee, Hyoung-No;Park, Han-Ju;Shoji, Tetsuo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.2
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    • pp.197-203
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    • 2001
  • Micro-defects induced by design and production failure or working environments are known as the cause of SCC(Stress Corrosion Cracking) in aged structures. Therefore, the evaluation of structural integrity based on micro-cracks is required not only a manufacturing step but also in-service term. So we introduce a new nondestructive inspection method using the magneto-optical film to detect micro-cracks. The method has some advantage such as high testing speed, real time data acquistion and the possibility of remote sensing by using of a magneto-optical film that takes advantage of the change of magnetic domains and domain walls. This paper introduces the concept of the new nondestructive inspection method using the magneto-optical film, also proves the possibility of this method as a remote testing system under oscillating load considering application on real fields by applying the method to four types of specimens.

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Micromechanical behavior of unidirectional composites under a transverse shear loading (횡방향 전단하중을 받는 단일방향 복합재료의 미시역학적 거동연구)

  • Choi, Heung-Soap;Achenbach, J.D.
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.11
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    • pp.1896-1911
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    • 1997
  • Effects of fiber-matrix interphases on the micro-and macro-mechanical behaviors of unidirectionally fiber-reinforced composites subjected to transverse shear loading at remote distance have been studied. The interphases between fibers and matrix have been modeled by the spring-layer which accounts for continuity of tractions, but allows radial and circumferential displacement jumps across the interphase that are linearly related to the normal and tangential tractions. Numerical calculations for basic cells of the composites have been carried out using the boundary element method. For an undamaged composite the micro-level stresses at the matrix side of the interphase and effective shear stiffness have been computed as functions of fiber volume ratio $V_f$ and interphase stiffness k. Results are presented for various interphase stiffnesses from the perfect bonding to the case of total debonding. For a square array composite the results show that for a high interphase stiffness k>10, an increase of $V_f$ increases the effective transverse shear modulus G over bar of the composite. For a relatively low interphase stiffness k<1, it is shwon that an increase of $V_f$ slightly decreases the effective transverse shear modulus. For the perfect bonding case, G over bar for a hexagonal array composite is slightly larger than that for a square array composite. Also for a damaged composite partially debonded at the interphase, local stress fields and effective shear modulus are calculated and a decrease in G over bar has been observed.

Development of the Vertical Ladder using a High-Strength Aluminium Alloys (6082-T6) (고강도 알루미늄 합금을 적용한 수직 사다리 개발 연구)

  • Kim, Jae-hyeong;Seo, Kwang-Cheol;Park, Joo-Shin
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.6
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    • pp.698-705
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    • 2020
  • In this study, an improved aluminum alloy (6082-T6) was used to develop a unique model of an aluminum ladder for usage in offshore plant. The structural strength design was carried out in accordance with international standards such as ISO, NORSOK Austria Standard. Load combination was performed to satisfy all conditions. The structural safety of the designed model was verified using SACS, an analysis program for offshore plants based on the Finite elements method. The analysis results confirmed that both stress and deflection were satisfied within the acceptance criteria. The developed model can be applied used in various fields in the near future as it meets all the necessary criteria and is lightweight and has improved productivity.

The use of the strain approach to develop a new consistent triangular thin flat shell finite element with drilling rotation

  • Guenfoud, Hamza;Himeur, Mohamed;Ziou, Hassina;Guenfoud, Mohamed
    • Structural Engineering and Mechanics
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    • v.68 no.4
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    • pp.385-398
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    • 2018
  • In the present paper, we offer a new flat shell finite element. It is the result of the combination of a membrane element and a bending element, both based on the strain-based formulation. It is known that $C^{\circ}$ plane membrane elements provide poor deflection and stress for problems where bending is dominant. In addition, they encounter continuity and compliance problems when they connect to C1 class plate elements. The reach of the present work is to surmount these problems when a membrane element is coupled with a thin plate element in order to construct a shell element. The membrane element used is a triangular element with four nodes, three nodes at the vertices of the triangle and the fourth one at its barycenter. Each node has three degrees of freedom, two translations and one rotation around the normal. The coefficients related to the degrees of freedom at the internal node are subsequently removed from the element stiffness matrix by using the static condensation technique. The interpolation functions of strain, displacements and stresses fields are developed from equilibrium conditions. The plate element used for the construction of the present shell element is a triangular four-node thin plate element based on Kirchhoff plate theory, the strain approach, the four fictitious node, the static condensation and the analytic integration. The shell element result of this combination is robust, competitive and efficient.

Functionally Gradient Materials (FGMs) for Improved Thermo-mechanical Properties (열.기계적 특성 향상을 위한 경사기능 재료 (FGM))

  • 박성용;김진홍;김문철;박찬경
    • Journal of Powder Materials
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    • v.11 no.1
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    • pp.8-15
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    • 2004
  • The basic concept of functionally gradient materials (FGM) is to fabricate materials type having possibilities of applications in various fields by changing their intrinsic properties with continuous gradient. The present communication has reviewed the developments and applications of various FGMs designed for improved thermo-mechanical properties, in which the thermal protective and wear resistant materials are especially focused. Effects of thermo-mechanical properties and limits of FGMs designed for high temperature applications were mainly understood in terms of residual stress evolved from the design and fabrication. In addition, FGMs applied in structural parts were also introduced and discussed in terms of typical fabrication method for FGMs.

Biological effects of zinc oxide nanoparticles on inflammation

  • Kim, Min-Ho
    • CELLMED
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    • v.6 no.4
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    • pp.23.1-23.6
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    • 2016
  • With the rapid developments in nanotechnology, an increasing number of nanomaterials have been applied in various aspects of our lives. Recently, pharmaceutical nanotechnology with numerous advantages has growingly attracted the attention of many researchers. Zinc oxide nanoparticles (ZnO-NPs) are nanomaterials that are widely used in many fields including diagnostics, therapeutics, drug-delivery systems, electronics, cosmetics, sunscreens, coatings, ceramic products, paints, and food additives, due to their magnetic, catalytic, semiconducting, anti-cancer, anti-bacterial, anti-inflammatory, ultraviolet-protective, and binding properties. The present review focused on the recent research works concerning role of ZnO-NP on inflammation. Several studies have reported that ZnO-NP induces inflammatory reaction through the generation of reactive oxygen species by oxidative stress and production of inflammatory cytokines by activation of nuclear factor-${\kappa}B$ ($NF-{\kappa}B$). Meanwhile, other researchers reported that ZnO-NP exhibits an anti-inflammatory effect by inhibiting the up-regulation of inflammatory cytokines and the activation of $NF-{\kappa}B$, caspase-1, $I{\kappa}B$ $kinase{\beta}$, receptor interacting protein2, and extracellular signal-regulated kinase. Previous studies reported that size and shape of nanoparticles, surfactants used for nanoparticles protection, medium, and experimental conditions can also affect cellular signal pathway. This review indicated that the anti-inflammatory effectiveness of ZnO-NP was determined by the nanoparticle size as well as various experimental conditions. Therefore, the author suggests that pharmaceutical therapy with the ZnO-NP is one of the possible strategies to overcome the inflammatory reactions. However, further studies should be performed to maximize the anti-inflammatory effect of ZnO-NP to apply as a potential agent in biomedical applications.