• Title/Summary/Keyword: Homogeneous

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A Comparative Quantitative Analysis of IDEAL (Iterative Decomposition of Water and Fat with Echo Asymmetry and Least Squares Estimation) and CHESS (Chemical Shift Selection Suppression) Technique in 3.0T Musculoskeletal MRI

  • Kim, Myoung-Hoon;Cho, Jae-Hwan;Shin, Seong-Gyu;Dong, Kyung-Rae;Chung, Woon-Kwan;Park, Tae-Hyun;Ahn, Jae-Ouk;Park, Cheol-Soo;Jang, Hyon-Chol;Kim, Yoon-Shin
    • Journal of Magnetics
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    • v.17 no.2
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    • pp.145-152
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    • 2012
  • Patients who underwent hip arthroplasty using the conventional fat suppression technique (CHESS) and a new technique (IDEAL) were compared quantitatively to assess the effectiveness and usefulness of the IDEAL technique. In 20 patients who underwent hip arthroplasty from March 2009 to December 2010, fat suppression T2 and T1 weighted images were obtained on a 3.0T MR scanner using the CHESS and IDEAL techniques. The level of distortion in the area of interest, the level of the development of susceptibility artifacts, and homogeneous fat suppression were analyzed from the acquired images. Quantitative analysis revealed the IDEAL technique to produce a lower level of image distortion caused by the development of susceptibility artifacts due to metal on the acquired images compared to the CHESS technique. Qualitative analysis of the anterior area revealed the IDEAL technique to generate fewer susceptibility artifacts than the CHESS technique but with homogeneous fat suppression. In the middle area, the IDEAL technique generated fewer susceptibility artifacts than the CHESS technique but with homogeneous fat suppression. In the posterior area, the IDEAL technique generated fewer susceptibility artifacts than the CHESS technique. Fat suppression was not statistically different, and the two techniques achieved homogeneous fat suppression. In conclusion, the IDEAL technique generated fewer susceptibility artifacts caused by metals and less image distortion than the CHESS technique. In addition, homogeneous fat suppression was feasible. In conclusion, the IDEAL technique generates high quality images, and can provide good information for diagnosis.

Nonlinear Analysis for the Prediction of Lateral Behavior of Single Piles in Non-homogeneous Sandy Soil (비균질 사질토 지반에서 단일말뚝의 수평거동 예측을 위한 비선형 해석기법)

  • 김영수;김병탁;허노영
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.5-16
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    • 2000
  • THe purpose of this paper is to suggest the analytical method which can predict lateral nonlinear behavior in non-homogeneous soil using the coefficient of soil resistance and ultimate soil resistance. Those parameters are obtained through back analysis on the base of the results of a series of model tests.Analytical method of Chang is more or less difficult to predict nonlinear behavior in non-homogeneous sol. So, in this study, for the prediction of nonlinear behavior the compositive analytical method which apply the p - y curve to Chang model is suggested. Also, the program is developed to predict nonlinear behavior using the compositive analytical method and it can be used to calculated the deflection, bending moment and soil reaction with DFM in non-homogeneous soil. To establish applicability of the suggested analytical method, the results of model tests and field tests and Pentagon2D finite element program are compared with those of the compositive analytical method. In the analysis values of the coefficient of soil reaction and ultimate soil resistance are also applied to the case of non-homogeneous soil. Lateral defection calculated using the compositive analytical method has been found to be in good agreement with values measured in field and model load tests.

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Analysis on Interactions of Creativity Homogeneous and Heterogeneous Team in Creative Robot Making and Programming Activities (창작 로봇 제작 및 프로그래밍 활동에서 창의성 동질 및 이질 팀 구성에 따른 팀 상호작용 분석)

  • Jo, Hanjin;Kim, Minwoong;Wi, Sunbok;Kim, Taehoon
    • Journal of Engineering Education Research
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    • v.19 no.5
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    • pp.13-24
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    • 2016
  • The purpose of this research is to examine the characteristics of team interaction according to the creativity of team members. Research subjects to achieve this purpose included 28 students who are in engineering education in the College of Education at A University in Daejeon and have taken robot-related courses. Through first and second MBTI, and TTCT tests, the final homogeneous and heterogeneous teams were formed, and an experimental study was conducted by developing team design activity assignment. The major research results were as follows. In terms of a comprehensive view on interaction frequency, both homogeneous team and heterogeneous team suggested had the highest frequency in suggesting opinions. However, each of the team members in the homogeneous team had different communication frequency among each other while each team member in the heterogeneous team had almost similar frequency. A microscopic analysis of the communication process of homogeneous team showed that the team members' roles were divided among each other in communication. Next, according to the microscopic analysis of the heterogeneous team's communication process, the team members exchanged opinions in the beginning, talked to themselves in words that were hard to understand the meanings, and they stopped having conversations in the end. Due to such decrease in communication, two team members could not solve the confusing state of being unable to understand each other's opinions and failed to complete their assignments. The microscopic analysis demonstrated that the homogeneous team had a smooth interaction, because when one team member suggested an opinion during a conversation, other team members agreed with it through a discussion. However, the members in the heterogeneous team experienced confusion as they could not understand each other's conversation and could not overcome this problem, leading to lack of conversations.

Copolymerization of Ethylene and α-olefins with Embedded rac-Et[Ind]2ZrCl2 Catalyst (Embedded rac-Et[Ind]2ZrCl2 메탈로센 촉매를 이용한 Ethylene/α-olefin 공중합특성)

  • Shin, Dong Min;Chung, Jin Suk
    • Korean Chemical Engineering Research
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    • v.46 no.1
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    • pp.137-141
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    • 2008
  • Copolymerization of ethylene and ${\alpha}$-olefin using $rac-Et[Ind]_2ZrCl_2/MAO$ catalyst embedded onto polysty-rene was examined. The embedded catalyst was prepared by polymerizing a small amount of styrene with $rac-Et[Ind]_2ZrCl_2$. The catalytic activities of the embedded catalyst were higher than those of the homogeneous catalystregardless of comonomer type and the characteristic of the active sites of the embedded catalyst was not affected duringthe embedding process. Based on the DSC and NMR analyses of the produced copolymers, it was thought that theembedded catalyst had similar or slightly better comonomer incorporation ability. Furthermore, the copolymers produced by the embedded catalyst had higher bulk densities and better particle morphology than those by the homogeneous catalyst.

Model Tests on the Characteristics of Lateral Behavior of Steel Pipe Pile in Homogeneous and Nonhomogeneous Soil Conditions (균질 지반과 비균질 지반에서 강관 모형말뚝의 수평거동 특성에 관한 모형실험)

  • 김병탁;김영수
    • Geotechnical Engineering
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    • v.14 no.6
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    • pp.153-166
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    • 1998
  • This paper shows the results of a series of model tests on the behavior of steel pipe pile which is subjected to lateral and inclined loads in homogeneous and non-homogeneous Nak-dong River sands. Non-homogeneous soil consisted of two layers, upper and lower layer. The purpose of the present paper is to investigate the effect of ratio of lower layer height to embedded pile length, ratio of soil modules of upper layer to lower layer and inclined load on the behavior of single pile. These effects can be quantified only by the results of model tests. As a result. in non-homogeneous sand soil, it is shown that the lateral behavior depends upon the ratio of soil modules of upper layer to lower layer more than other factors. And it was found that the relationship between the deflection ratio of non-homogeneous sand to homogeneous sand and the ratio of lower layer height to embedded pile length can be fitted to exponential function of H/L by model tests results. For the inclined load applied, it is shown that the bending moment-depth relationship is not similar to the case of laterally loaded pile and the depth of maximum bending moment at relative density of 90% increases about 70% more than the pile only loaded laterally.

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A NOTE ON ENERGY MINIMIZING MAP ON MANIFOLD WITH ISOLATED PEAKS

  • SHIN, HEAYONG
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.6 no.1
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    • pp.59-65
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    • 2002
  • In this paper, we consider some homogeneous maps from a cone over 2-spheres and determines whether they become energy minimizing maps or not. In fact, any homogeneous map from a standard cone over 2-sphere of radius smaller than 1 can not be a minimizing harmonic map.

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AREA INTEGRALS WITH A MEASURE ON GROUPS OF HOMOGENEOUS TYPE

  • Suh, Choon-Serk
    • Bulletin of the Korean Mathematical Society
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    • v.32 no.1
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    • pp.115-121
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    • 1995
  • We define a group of homogeneous type G which is a more general setting than $R^n$. This group G forms a natural habitat for extensions of many of the objects studied in Euclidean harmonic analysis.

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