• Polymer(Korea)
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• v.32 no.4
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• pp.353-358
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• 2008

Maleated ethylene-propylene-diene terpolymer (MEPDM) was prepared from solution polymerization of EPDM and maleic anhydride. MEPDM-grafted-poly (dimethylsiloxane) (PDMS) copolymer (MEPDM-g-PDMS) was prepared from copolymerization of MEPDM with $\alpha$,$\omega$-hydroxyl group terminated PDMS. The MEPDM-g-PDMS was compounded with HDPE and 4-ethoxybenzoic acid modified MWCNT at $180^{\circ}C$ and positive temperature coefficient (PCT) behavior of the MWCNT composite was investigated. Surface modification of MWCNT enabled it to be more uniformly dispersed in polymer matrix and decreased aggregation of particles. Electrical resistivity of the composite was abruptly increased at melting temperature and PTC intensity of 2.3 was obtained at 15% loading of surface modified CNT.

• Korean Journal of Materials Research
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• v.16 no.11
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• pp.668-675
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• 2006

In the partial squeeze casting process, the filling behavior of liquid metal and solidification pattern in thick area have significant influence on the quality of casting products and die life. For the optimal casting design of automobile transmission gear housing, various analyses were performed in this study by using computer simulation code, MAGMAsoft and the simulation results were compared and analyzed with experimental results. By air pressure criteria, internal porosities caused by air entrap during the mold filling were predicted and reduced remarkably by modification of gating system. Also, optimal squeeze-time lag to apply partial squeeze pin in thick area was calculated and the castings was free from shrinkage defects with the result of solidification analysis. Consequently, casting design for automobile transmission gear housing was optimized and approved by Computer Tomography.

• Elastomers and Composites
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• v.56 no.1
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• pp.6-11
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• 2021

In order to develop an ultra-high-density elastomeric material for substitution of steel dynamic dampers, a new curing system and technique for high-loading of the filler were examined in this study. Mechanochemical modification of chloroprene rubber (MAH-g-CR) using an internal mixer was carried out with maleic anhydride (MAH) as a reactive monomer. The optimum amount of MAH was 10 phr and the efficient grafting of MAH on CR could be achieved at a mixing temperature of 100℃. After preparing MAH-g-CR, 50 mol% epoxidized natural rubber (ENR 50) was blended with MAH-g-CR to develop a "self-curable rubber blend system" via reaction between the functional groups of the elastomeric matrices without the curing agent and additives. The content of ENR 50 was fixed at 30 wt.% throughout evaluation of the curing behavior of the MAH-g-CR/ENR blend. Tungsten powder was added to the MAH-g-CR/ENR matrix up to 60 vol.% to obtain ultra-high-density, and the maximum density obtained was 7.57 g/㎤. Stable ts2 (scorch time) and t90 (90% cure time) could be obtained even when tungsten powder was incorporated up to 60 vol.%. In addition, the tensile strength and damping properties of MAH-g-CR/ENR containing 60 vol.% of tungsten were better than those of CR containing 60 vol.% of tungsten.

• Journal of Preventive Medicine and Public Health
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• v.34 no.3
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• pp.211-218
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• 2001

Objectives : To develop a Korean version of VSSS-82 for measuring the multi-dimensional satisfaction with community-based mental health services in psychiatric patients and to investigate both the reliability and validity of the Korean version. Methods : The VSSS-82 English version was translated and back-translated with some modification. Data from 68 psychosis patients using community-based mental health services in three Community Mental Health Centers (CMHCs) was collected through a personal interview survey regarding the satisfaction and suitability of service. Variability of satisfaction and internal consistency, discriminant validity, and concurrent validity of the VSSS-82 Korean version were evaluated. Results : A higher number of dissatisfied subjects and significant pairwise differences for the dimensions were found. The Crohnbach's alpha coefficient, a measure of internal consistency, ranged from 0.56(overall satisfaction) to 0.90(skills and behavior) and significant differences in satisfaction was found in patients by the self-rated suitability of service. Conclusions : The VSSS-82 Korean version is a reliable and valid instrument for measuring multi-dimensional satisfaction with community-based mental health service.

• Tribology and Lubricants
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• v.34 no.6
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• pp.270-278
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• 2018

STS 316L prepared by additive manufacturing (AM) exhibits deterioration of mechanical properties and wear resistance due to the presence of defects such as black-of-fusion defects, internal porosity, residual stress, and anisotropy. In addition, high surface roughness (integrity) of AM products remains an issue. This study aimed to apply ultrasonic nanocrystal surface modification (UNSM) technology to STS 316L prepared by AM to increase the surface hardness, to reduce the surface roughness, and to improve the friction and wear behavior to the level achieved by bulk material manufactured using traditional processes. Herein, the as-received and polished specimens were treated by UNSM technology and their resulting properties were compared and discussed. The results showed that UNSM technology increased the surface hardness and reduced the surface roughness of the as-received and polished specimens. These results can be attributed to grain size refinement and pore elimination from the surface. Moreover, the friction of the as-received and polished specimens after UNSM technology was lower compared to those of the as-received and polished specimens, but no significant differences in wear resistance were found.

• Journal of Community Nutrition
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• v.3 no.1
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• pp.21-29
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• 2001

This study was conducted to examine factors with attendance in hyperlipidemia nutrition eduction program among 101 hyperlipidemic outpatients (38 males 63 females) at Samsung Medical Center We employed the Health Belief Model (HBM) as the theoretical framework The individual nutrition education and counseling program was scheduled with 4- half hour session sin 2 to 4 weeks intervals. Upon initiation of the program a trained dietitian surveyed HBM constructs and psychosocial factors. The following were included perceived susceptibility to cardiovascular disease(CVD) perceived severity to CVD percieved benefits to diet modification perceived barriers to persistence in maintaining therapy and self efficicacy and social support from family Sociodemographic data health factors stress level nutrition knowledge, and 24-hour dietary recall behavior were also surveyed All these data was analyzed according to the number of nutrition sessions attended The subjects were 55.9$\pm$9.4 year old and 24.6$\pm$kg/㎡ Sociodemographic factors were not associated with the number of nutrition sessions attended HBM constructs and psychosocial factors were significantly associated with the number of nutrition sessions attended. According to Spearman correlation coefficients. From stepwis regression analyses using HBM constructs as independent variables perceive barriers to persistence in maintaining diet therapy (negative) proved to be the strongest predictors for the number of nutrition sessions attended (partial R$^2$= 72.3%) followed by perceived severity to CVD and self efficacy (model R$^2$=76.6% The findings indicate that HBM constructs and psychosocial factors were closely associated with patient attendance It suggests that information and guidance to minimize patients perceived barriers to diet therapy might help to improve patients to scheduled appointments in nutrition education programs.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.166-176
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• 1994

Ni base superalloys are composed of solid sohltion hardening elements(Co, Cr. Mo. W and so on) and $\gamma '$ precipitation hardening elements(A1, Ti, Nb, Ta and so on). To Improve the mechanical properties and oxidation resistanre of superalloys, rare earth elements(%r, Hf, Y and so on) are added to the inner substrate, or are used as coating materials. Their pffects on the growth rate and adhes~on of oxide are changed according to the kinds of oxides such as $AI_2O_3$ and $Cr_2O_3$. The effect of yttrium on the oxidation rate, grain size of oxide, internal structure, and crack resistance was investigated for two kinds of Ni-base superalloys. One in AF'115 superalloy containing Hf and the other is MA6000 superalloy containing $Y_2O_3$. They werr owid~zed at high temperature after yttrium surface modification using ion coater. Yttrium coating on the AF115 and MA6000 superalloys results in a marked change in the growth of the inner oxide. For AF115 superalloy, the degree of gram boundary segregation of $Cr_2O_3$, and prefer en^ tial oxidation of Hf are decreased, and the shape of inner oxidation layer was changed from triangle to plate type. For MA6000 superalloy, $Cr_2O_3$ oxide scale was transformed as outer oxidation layer of CrZOI and inner oxidation layer of $Cr_2O_3$.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.115-127
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• 2008

The component for satisfying several domain requirements must be developed to support variety. But, when the application is developed using the component, it happens other requirements. So, it is difficult to design component to satisfy severaldomain requirements. Also, it is impossible to support the special business logic. As this problem, the component must provide to the white-box component, it is not the black-box component. So, in this paper, we propose the variability design technique and the customization technique using the design technique that can support the various requirements. This technique is not focus on designing the component to analyze various domains. The variability of the component is designed to the initial variability in the component development phase and we use the customization technique for applying the variability to developing application. The variability can be re-designed during developing the application to use the component applying the variability. The variability of the component is evolved and the generation of the component is increased via the iteration Generally, the range of the component variability is classified the function modification within the component and the component internal structure modification as requirements in the component outside. As the range of the variability, we propose the variability design technique of the behavior and the message flow. This paper proposes a message flow design technique for modifying function call.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.81-92
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• 2011

The rheological properties of Wyoming bentonites are strongly influenced by the size of particles, cation exchangeable capacity, arrangement and morphology of clay mineral. This paper presents the results of rheological investigations on the Wyoming bentonites aqueous dispersions: two types of particle flocculation were considered. For the Wyoming bentonite, 0g/L and 30g/L NaCl equivalent salinity were added in fresh and salt water to examine the rheological behavior. This paper examined the general rheological characteristics, compatibility of rheological models and correlation between soil structure and change in rheological properties of Wyoming bentonite caused by increasing salinity. From flow curves of bentonites hydrated with fresh water and salt water, the observed general flow behavior is very close to shear thinning with yield stress (or ideal Bingham fluid with yield stress and plastic viscosity). However, the change of shear stress at the same shear rate is clear, particularly for lower shear rate. Well-known rheological models are used to fit the data. There is a good agreement between rheological model and data: Carreau, Herschel-Bulkley and power-law for S=0g/L and bilinear, Herschel-Bulkley and power-law for S=30g/L. It may be due to the fact that the internal structural bonding (strong modification of particle-particle interactions from edge-to-edge and/or edge-to-face to face-to-face) in soil matrix is affected from the evolution of rheological properties with different salinities.

• Development and Reproduction
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• v.12 no.2
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• pp.117-124
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• 2008

The efficient strategies to cope with unpredictable and/or harmful environmental changes have been developed by every organism in order to ensure its survival and continuity of it's own species. As a results, all living things on earth maintain dynamically internal stability via a process termed 'homeostasis' among physiological parameters despite of external environment changes. Stress is an emotional and physical response to threat homeostasis. Stress may have not only transient but rather permanent effect on the organism; recent evidence clearly show that prenatal stress could organize or imprint permanently physiological systems without any change in genetic codes, a process known as 'epigenetic programming'. In this review, a series of reproduction-associated events occurred in prenatally stressed male rats such as alteration in the structure of sexually dimorphic brain regions, modification of neurotransmitter metabolism, changes in reproductive endocrine status, and finally, disorders of sexual behavior will be introduced. The fetal brain is highly sensitive to prenatal programming and glucocorticoids in particular have powerful brain-programming properties. The chronic hyperactivation of fetal brain by maternal stress-induced glucocorticoid input will provide new program via increasing the neuroplasticities. This 'increased neuroplasticities' will be the basis for the 'increased phenotypic plasticities' rendering the organism's better adaptation to environmental challenges. In conclusion, organism who experienced 'harsh' environment in his fetal life seems to give up a certain portion of reproductive competence to make good chance of survival in his future life by epigenetic (re)programming.