• 제목/요약/키워드: non-homogeneity effect

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의복관여 효과에 대한 메타분석 (Synthesis of Primary Studies Related to Clothing Involvement by Meta-analysis)

  • 이종남;유혜경
    • 한국의류학회지
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    • 제37권3호
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    • pp.386-398
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    • 2013
  • This study analyzes the effect of clothing involvement using meta-analysis. Metal-analysis (the analysis of analyses) is widely used in various academic areas to integrate individual empirical studies and generalize the knowledge of a specific research field. Previous studies regarding clothing involvement published since 1990 were researched from the KISS database using clothing involvement and fashion involvement as a keyword; subsequently, 127 articles were identified. Studies that had insufficient statistics or included clothing involvement as a moderating (or intervening variable) were eliminated; subsequently, 36 articles provided a total of 75 data sets that were used for the final analysis. Dependent variables were grouped into 10 categories to compare the differences between high and low involvement groups. The effect size of clothing involvement was large in non-personal information source; however, it was small in utility, brand royalty and quality. In the 7 categories of relational studies that showed homogeneity, the relation size regarding conformity was smaller than the personal information source.

Computational study of the wave propagation in three-dimensional human cardiac tissue

  • Kwon, Soon-Sung;Im, Uk-Bin;Kim, Ki-Woong;Lee, Yong-Ho;Shim, Eun-Bo
    • International Journal of Vascular Biomedical Engineering
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    • 제3권1호
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    • pp.23-29
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    • 2005
  • We developed a three dimensional cardiac tissue model based on human cardiac cell and mono-domain approximation for action potential propagation. The human myocyte model proposed by ten Tusscher et al. (TNNP model) (2004) for cell electrophysiology and a mono-domain method for electric wave propagation are used to simulate the cardiac tissue propagation mechanism using a finite element method. To delineate non-homogeneity across cardiac tissue layer, we used three types of cardiac cell models. Ansiotropic effect of action potential propagation is also considered in this study. In this 3D anisotropic cardiac tissue with three cell layers, we generated a reentrant wave using S1-S2 protocol. Computational results showed that the reentrant wave was affected by the anisotropic properties of the cells. To test the reentrant wave under pathological state, we simulated a hypertopic model with non-excitable fibroblasts in stochastic manner. Compared with normal tissue, the hypertropic tissue result showed another center of reentrant wave, indicating that the wave pattern can be more easily changed from regular with a concentric focus to irregular multi-focused reentrant waves in case of patients with hypertrophy.

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다기통 전기점화기관의 혼합기 불균일화가 사이클 변동에 미치는 영향 (I) (Effect of Non-Uniform Mixture on Cycle Fluctuation of Multi-Cylinder Spark Ignition Engine(I))

  • 송재학;이용길;박경석;양옥룡
    • 대한기계학회논문집
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    • 제16권9호
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    • pp.1736-1743
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    • 1992
  • 본 연구에서는 기화기부착 4행정 4기통 전기점화기관을 사용하여 흡기관내 액 막흐름에 의한 연료의 불균일화가 기관의 연소특성과 배기특성에 미치는 영향을 규명 하는데 궁극적인 목적을 두고 우선, 연소특성을 해석하기 위하여 비교적 고가인 연소 해석 시스템을 개발하는데 1차적인 목적으로 하였으며, 시험제작한 연소해석 시스템으 로 액막흐름의 가시화 및 배기가스 농도측정과 지압선도 해석을 행하여 구조적으로 대 칭인 1번과 4번 실린더의 연소특성과 배기특성을 비교 검토하였다.

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

  • Hernandez, Daniel;Kim, Kyoung-Nam
    • Investigative Magnetic Resonance Imaging
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    • 제24권3호
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    • pp.95-122
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    • 2020
  • In this article, we evaluated the performance of radiofrequency (RF) coils in terms of the signal-to-noise ratio (S/N) and homogeneity of magnetic resonance images when used for ultrahigh-frequency (UHF) 7T magnetic resonance imaging (MRI). High-quality MRI can be obtained when these two basic requirements are met. However, because of the dielectric effect, 7T magnetic resonance imaging still produces essentially a non-uniform magnetic flux (|B1|) density distribution. In general, heterogeneous and homogeneous RF coils may be designed using electromagnetic (EM) modeling. Heterogeneous coils, which are surface coils, are used in consideration of scalability in the |B1| region with a high S/N as multichannel loop coils rather than selecting a single loop. Loop coils are considered state of the art for their simplicity yet effective |B1|-field distribution and intensity. In addition, combining multiple loop coils allows phase arrays (PA). PA coils have gained great interest for use in receiving signals because of parallel imaging (PI) techniques, such as sensitivity encoding (SENSE) and generalized autocalibrating partial parallel acquisition (GRAPPA), which drastically reduce the acquisition time. With the introduction of a parallel transmit coil (pTx) system, a form of transceiver loop arrays has also been proposed. In this article, we discussed the applications and proposed designs of loop coils. RF homogeneous coils for volume imaging include Alderman-Grant resonators, birdcage coils, saddle coils, traveling wave coils, transmission line arrays, composite right-/left-handed arrays, and fusion coils. In this article, we also discussed the basic operation, design, and applications of these coils.

국내 연구의 패션상품 평가속성 효과에 대한 메타분석연구 (Meta-analysis on the Effects of Fashion Product Evaluation Attributes in Korea)

  • 이정우;김미영
    • 한국의류학회지
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    • 제40권6호
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    • pp.1150-1163
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    • 2016
  • This study makes use of meta-analysis to statistically integrate the quantitative results of individual research on the influence of fashion product attributes on purchase; in addition, this study utilizes the effect sizes of correlation coefficients. This study was based on 24 individual studies from January 2000 to March 2015. The meta-analysis analyzed 91 effect sizes and 24 studies and calculated the correlation coefficient effect sizes. A random effect model was employed for meta-analysis because the results for the homogeneity test indicated that the effect sizes of each research were heterogeneous. The analysis results are as follows. First, when the total effect sizes of the fashion product attributes that influence clothing purchase decisions were calculated as .256; this indicated that the effect size is slightly below the mid-sized level. Second, upon examining the effect sizes of the categorized fashion product attributes, the intrinsic attributes yielded .222, extrinsic factors yielded .235, and the compiled attributes yielded .420; this demonstrated that the compiled attributes have a larger effect size than individual attributes. Third, when they were measured by the characteristics of study targets, they were larger for a mixed-gender group than women as well as for ordinary citizens than university students. When the effect sizes were measured based on the characteristics of fashion products as suggested in the study, there were significant differences with respect to sportswear, followed by SPA brand clothing, general clothing, fashion accessories, and designer clothing. The cases where the clothing were purchased in non-retail stores were found to have a slightly larger effect size than those of offline retail stores when the effect sizes were measured based on purchase routes; however, the difference was not statistically significant. Next, an investigation of the trend of effect sizes based on published year via the meta regression analysis indicated slightly larger effect sizes as shown in more recent publications, but this was not statistically significant.

생리식염액을 이용한 구강간호가 중환자실 환자의 구강상태에 미치는 효과 (The Effect of Oral Care with Normal Saline on Oral State of Patients in Intensive Care Unit)

  • 최선희;김영경
    • 성인간호학회지
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    • 제16권3호
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    • pp.452-459
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    • 2004
  • Purpose: To investigate the effect of oral care either with normal saline or with tantum solution on the oral state of the patients in intensive care unit as well as the frequency of bacteria occurrence inside their oral cavities. Method: The study was performed from March thru May of 2003 on the nonequivalent control group non-synchronized quasi-experimental design. Forty subjects were selected for each group. The data were analyzed using the SPSS 10.0 Win. The pre-experimental homogeneity and post-experimental differences between the two groups were analyzed with t-test. Result: There was a significant difference in the oral cavity state between the experimental group that had used normal saline and the control group that had used tantum solution. Conclusion: Based on the results described above, it is considered that normal saline is more effective than the tantum solution for the oral care of the patients in intensive care unit.

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열전달 해석을 통한 스크롤 압축기 성능 개선 (Performance Improvement of a Scroll Compressor by Heat Transfer Analysis)

  • 홍상욱;류호선
    • 한국유체기계학회 논문집
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    • 제3권4호
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    • pp.22-29
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    • 2000
  • Numerical analysis using three dimensional finite volume method for the discretization, adaptive grid method for the numerical accuracy, multiple rotating frame method for the rotating body and the standard $k-{\epsilon}$ model for the turbulent flow was performed to understand the heat transfer phenomena and to improve the efficiency of the scroll compressor. The temperature measurement was carried out under ARI condition. It was found that the fluid temperature in the compressor was predicted accurately while the temperature of the motor coil showed large discrepancy between the calculation and experiment due to the large anisotropy of the conductivity and non homogeneity. We found that the efficiency of the compressor depends on the inlet temperature of the compressing part and the flow pattern around the inlet region of the compressing part influences the inlet temperature due to high surface temperature of the main frame. The efficiency of the compressor using Coanda effect is higher than the previous one because the smooth suction at the inlet region of the compressing part leads to low heat transfer to the refrigerant of the compressor.

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상지경혈지압이 편마비환자의 상지기능과 일상생활동작 시 불편감에 미치는 효과 (Effect of the Meridian Pressure on the Functions of Upper Extremities and Discomfort of ADLs of Hemiplegic Patients)

  • 김정화;최성남
    • 성인간호학회지
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    • 제20권1호
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    • pp.55-64
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    • 2008
  • Purpose: The purpose of this study was to identify the effect of Meridian pressure on the functions of upper extremities and discomfort of ADLs of hemiplegic patients. Methods: The research design was a nonequivalent control group, non-synchronized design. Subjects were 35 hemiplegic patients who were hospitalized at L Oriental Medical Hospital; 18 for the experimental group and 17 for the control group. The experimental group was given meridian pressure for 10 minutes daily for 2 weeks. The data were analyzed by SPSS 12.0 program. The ${\chi}^2$-test and t-test were used for the two groups' homogeneity, and t-test was used for the hypothesis test. Results: Manual muscle test, ROMs of wrist extension, elbow flexion, and shoulder extension of the experimental group increased compared to the control group. Shoulder pain and index finger circumference of the experimental group decreased compared to the control group. The experimental group showed to have less discomfort of ADLs than the control group. Conclusion: The study results verified that meridian pressure is effective for improving the functions of hemiplegic patients' upper extremities as well as reducing discomfort of ADLs.

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Mesoscale modelling of concrete for static and dynamic response analysis -Part 2: numerical investigations

  • Lu, Yong;Tu, Zhenguo
    • Structural Engineering and Mechanics
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    • 제37권2호
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    • pp.215-231
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    • 2011
  • As a brittle and heterogeneous material, concrete behaves differently under different stress conditions and its bulk strength is loading rate dependent. To a large extent, the varying behavioural properties of concrete can be explained by the mechanical failure processes at a mesoscopic level. The development of a computational mesoscale model in a general finite element environment, as presented in the preceding companion paper (Part 1), makes it possible to investigate into the underlying mechanisms governing the bulk-scale behaviour of concrete under a variety of loading conditions and to characterise the variation in quantitative terms. In this paper, we first present a series of parametric studies on the behaviour of concrete material under quasi-static compression and tension conditions. The loading-face friction effect, the possible influences of the non-homogeneity within the mortar and ITZ phases, and the effect of randomness of coarse aggregates are examined. The mesoscale model is then applied to analyze the dynamic behaviour of concrete under high rate loading conditions. The potential contribution of the mesoscopic heterogeneity towards the generally recognized rate enhancement of the material compressive strength is discussed.

BTR공법의 시공단계별 안전성 해석 (A Safety Analysis of the BTR Method by Construction Sequence)

  • 정광모;이원희;이상헌;방명석
    • 대한안전경영과학회지
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    • 제14권1호
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    • pp.101-108
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    • 2012
  • In this study was conducted numerical analysis to evaluate the stability of BTR(Built-in Timber Roof Tunneling Method), which is one of construction methods of underground structures in the non-opening state. The discretion method was applied to individually model reinforcing members of BTR, and the homogeneity analysis technic by area ratio was used to verify the feasibility comparing this result with that from conventional analysis method. The parameter study was performed to evaluate the effect varying ground depth, distance length of reinforcing supports and to verify the field applicability of new analysis method. The results showed the very precise value with allowable error, so this method can be applied in the field, The more length of supporting members caused the more vertical displacement and the top displacement increment of support members is larger than that of ground surace. The effect of ground depth was more impressive than that of distance length of reinforcing supports.