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여종일,Karen Weihs,DAVID REISS 한국청소년학회 2014 청소년학연구 Vol.21 No.10
This study investigated family relationship, parenting behaviors, and adolescents’ adjustment to families with depressed parents. Fifty-eight adolescents completed questionnaires measuring family relationship quality as well as internalizing and externalizing symptoms. Parents reported current depressive symptoms and their parenting behaviors. Results revealed that adolescent-reported family relationship quality was associated with adolescents’ internalizing and externalizing symptoms when controlling parental current depressive symptoms. Lower levels of parent-reported acceptance were associated with adolescents’ externalizing symptoms. These preliminary findings highlight the need to understand the family environments of adolescents with depressed parents and the importance of enhancing family cohesion and parental acceptance while treating depressed parents. Implications, limitations, and recommendations for future research are discussed.
Yuh, Jongil,Weihs, Karen,Reiss, David The Korean Home Economics Association 2013 International Journal of Human Ecology Vol.14 No.2
This study investigated the differences between adolescents' own perceptions of their psychopathology and perceptions by clinically depressed parents of their adolescents' psychopathology. The study also examined parental characteristics that accounted for discrepancies between parents and adolescents. The clinical sample consisted of 61 adolescents and their parents who were diagnosed with a major depressive disorder. The adolescents and parents evaluated the adolescents' psychopathology in separate interviews with the Child Behavior Checklist (CBCL) and the Youth Self-Report (YSR). Parents reported on current depressive symptoms and parenting practices using questionnaires. The results revealed that parent-adolescent discrepancies were greater in regard to affective and anxiety problems compared to oppositional defiant and conduct problems. Parental rejection was associated with differences in scores for affective problems after controlling for parents' current depressive symptoms and adolescents' age and gender. The findings highlight the importance of considering adolescents' affective and anxiety problems when treating depressed parents. Furthermore, the findings suggest that parental rejection may play a pivotal role when interpreting the discrepancy concerning adolescents' affective problems.
( Jongil Yuh ),( Karen Weihs ),( David Reiss ) 대한가정학회 2013 International Journal of Human Ecology Vol.14 No.2
This study investigated the differences between adolescents` own perceptions of their psychopathology and perceptions by clinically depressed parents of their adolescents` psychopathology. The study also examined parental characteristics that accounted for discrepancies between parents and adolescents. The clinical sample consisted of 61 adolescents and their parents who were diagnosed with a major depressive disorder. The adolescents and parents evaluated the adolescents` psychopathology in separate interviews with the Child Behavior Checklist (CBCL) and the Youth Self- Report (YSR). Parents reported on current depressive symptoms and parenting practices using questionnaires. The results revealed that parent-adolescent discrepancies were greater in regard to affective and anxiety problems compared to oppositional defiant and conduct problems. Parental rejection was associated with differences in scores for affective problems after controlling for parents` current depressive symptoms and adolescents` age and gender. The findings highlight the importance of considering adolescents` affective and anxiety problems when treating depressed parents. Furthermore, the findings suggest that parental rejection may play a pivotal role when interpreting the discrepancy concerning adolescents` affective problems.
Surface Tension of Magneto-Rheological Fluids
Shai Rahimi,Daniel Weihs 한국자기학회 2016 Journal of Magnetics Vol.21 No.2
Surface tension is a major factor in the thermodynamics as well as fluid properties of Magneto-Rheological Fluids (MRF). We measured the surface tension of an MRF using two different methods. A wettability characterization based on contact angles measurements for the fluid interacting with two different surfaces was conducted. A hydrocarbon based commercial MRF with more than 80% solid weight, placed on quartz and poly-tetra-fluoroethylene (PTFE) surfaces was used. We measured the fluids" surface tension value by means of contact angles measurements and by the falling drop method.
Fabrication and mechanical characterization of 3D woven Cu lattice materials
Zhang, Y.,Ha, S.,Sharp, K.,Guest, J.K.,Weihs, T.P.,Hemker, K.J. Elsevier Ltd 2015 Materials & Design Vol.85 No.-
3D metallic lattices designed to have two distinctly different material architectures have been woven with metallic Cu wires. A vacuum soldering technique was employed to metallurgically bond the wire nodes and form stiff 3D lattice materials. The structures and mechanical properties of the as-woven and soldered lattices were characterized by optical microscopy and micro-scale mechanical property experiments. The measured in-plane shear stiffness shows good agreement with predictions from finite element (FE) models that account for variations in the manufacturing and solder bonding. The study indicates that stiffness is influenced by the percentage of bonded nodes and the location of bonding. The 3D woven lattice materials manufactured in this study exhibited a very high percentage (80%) of bonded nodes and a unique combination of stiffness and density as compared to that typically reported for ultra lightweight lattice materials.
Sim, Gi-Dong,Krogstad, Jessica A.,Xie, Kelvin Y.,Dasgupta, Suman,Valentino, Gianna M.,Weihs, Timothy P.,Hemker, Kevin J. Elsevier 2018 Acta materialia Vol.144 No.-
<P><B>Abstract</B></P> <P>Advanced metallic alloys are attractive in microelectromechanical systems (MEMS) applications that require high density, electrical and thermal conductivity, strength, and dimensional stability. Here we report the mechanical behavior of direct current (DC) magnetron sputter deposited Nickel (Ni)-Molybdenum (Mo)-Tungsten (W) films annealed at various temperatures. The films deposit as single-phase nanotwinned solid solutions and possess ultra-high tensile strengths of approximately 3 GPa, but negligible ductility. Subsequent heat treatments resulted in grain growth and nucleation of Mo-rich precipitates. While films annealed at 600 °C or 800 °C for 1 h still showed brittle behavior, films annealed at 1,000 °C for 1 h were found to exhibit strength greater than 1.2 GPa and near 10% tensile ductility. In addition to the excellent mechanical properties, alloy films further exhibit remarkably improved dimensional stability – a lower coefficient of thermal expansion and greater microstructural stability. An excellent balance between mechanical properties and dimensional stability make sputter deposited Ni-Mo-W alloys promising structural materials for MEMS applications.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Zhao, Longyu,Ryan, Stephen M.,Lin, Sen,Xue, Ju,Ha, Seunghyun,Igusa, Takeru,Sharp, Keith W.,Guest, James K.,Hemker, Kevin J.,Weihs, Timothy P. Elsevier 2017 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.108 No.2
<P><B>Abstract</B></P> <P>The fluidic and heat transfer capabilities of 3D woven lattice materials were reported recently under axial and bifurcated flow patterns, but three critical performance indices – pressure drop, average surface temperature and temperature uniformity – could not be optimized simultaneously using these flow patterns. Here we combine the 3D weaves with manifolds to create a novel 3D flow pattern that enhances temperature uniformity, while also maintaining low pressure drops and surface temperatures. These three properties were characterized at room temperature for a range of flow rates using water as the working fluid. Three different weaves thicknesses were investigated: 12.7mm, 6.4mm, and 3.2mm, with manifold thicknesses of 12.7mm, 19.0mm, and 22.2mm, respectively, to provide a constant, combined weave-manifold thickness of 25.4mm. The properties of this new weave/manifold system are compared to those obtained using just the manifold (with no weave) and just the weave (with no manifold). Comparisons show that the addition of the weave lowers the average substrate temperature and temperature variations significantly, although pressure drop is increased. They also show that the addition of the manifold improves temperature uniformity significantly, and also lowers the average substrate temperature and the pressure drop. No specific ratio of weave to manifold thickness was found to be superior in all of the performance indices. The thermal performances are then evaluated at different pumping powers: the weave/manifold system and its distributed array flow pattern prevail. Finite element simulations were performed on a reduced and simplified model to explain the observed experimental trends, and manifold opening patterns were manipulated to demonstrate further potential property enhancements. The multiple benefits of this manifold system can be extended to common heat exchanger media beyond weaves.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Propose and design novel flow manifold that is combined with 3D woven lattices. </LI> <LI> Characterization of pressure drop, average temperature and temperature uniformity. </LI> <LI> Much superior thermal performance with 3D woven lattices than open spaces. </LI> <LI> Comparison of the new distributive flow pattern with axial and bifurcated flow cases. </LI> <LI> Trends between experiments and simulations are in good agreement. </LI> </UL> </P>