• Title/Summary/Keyword: PHR1

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Cure Kinetics of Natural Zeolite/Epoxy Composites (천연 제올라이트/에폭시 복합재료의 경화반응 속도론)

  • Lee, Jae-Young;Chun, In-Sook;Shim, Mi-Ja;Kim, Sang-Wook
    • Applied Chemistry for Engineering
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    • v.7 no.2
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    • pp.387-392
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    • 1996
  • Natural zeolite/epoxy resin composites were prepared and the cure kinetics was studied by dynamic DSC analysis. With the increments of natural zeolite content, the reaction starting temperature and the exothermic peak temperature were decreased. When diglycidyl ether of bisphenol A(DGEBA)/4,4'-methylene dianiline(MDA)/malononitrile(MN, 10phr) was filled with 20phr of zeolite, DSC thermogram had one peak and when it was filled with 30phr of zeolite, a shoulder appeared on the DSC thermogram. With the filling of 40phr of zeolite, DSC thermogram was separated into two peaks and the activation energy of the first peak, $Ea_1$ was 12.30 kJ/mol and that of the second peak, $Ea_2$ was 12.70 kJ/mol.

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Effect of Additive-added Epoxy on Mechanical and Dielectric Characteristics of Glass Fiber Reinforced Epoxy Composites (유리섬유강화 에폭시 레진 복합체의 기계적, 유전체 특성에 미치는 첨가제 함유 에폭시 영향)

  • Vu, Cuong Manh;Nguyen, Liem Thanh;Nguyen, Thai Viet;Choi, Hyoung Jin
    • Polymer(Korea)
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    • v.38 no.6
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    • pp.726-734
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    • 2014
  • Three different types of additives, thiokol, epoxidized natural rubber (ENR) and epoxidized linseed oil (ELO), were dispersed in an epoxy matrix before being used in glass fiber (GF) composites, and their effects on the mechanical and dielectric properties of epoxy resin and glass fiber reinforced epoxy composites (GF/EP) were examined. The addition of each of 7 phr ENR, 9 phr ELO and 5 phr thiokol into the epoxy resin increased the fracture toughness significantly by 56.9, 43.1, and 80.0%, respectively, compared to the unmodified resin. The mode I interlaminar fracture toughness of the GF/EP at propagation was also improved by 26.9, 18.3 and 32.7% when each of 7 phr ENR, 9 phr ELO, and 5 phr thiokol, respectively, was dispersed in the epoxy matrix. Scanning electron microscopy showed that the additives reduced crack growth in the GF/EP, whereas their dielectric measurements showed that all these additives had no additional effect on the real permittivity and loss factor of the GF/EP.

What kind of specialized services attract patients? (환자유치를 위한 특화서비스에 대한 연구)

  • Lee, Yong-Woong;Jeong, Yeong-Sik;Kim, Yun-Ji;Baek, Eun-Hae;Rhee, Hyun-Sill
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.12
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    • pp.4954-4961
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    • 2010
  • Background: Competition among hospitals has intensified, because hospitals and beds are oversupplying and the global medical market has opened in Korea. Method: we developed questionnaires of the patient's satisfaction about 20 items. We surveyed 297 out-patients and 302 in-patients. We analyzed the descriptive statistics and regression by SPSS(Version 17) and Excel. Results: The relations with the patient's loyalty and the specialized hospital service are 1) Recommend to other person: FHR use and the assistant for follow-up treatment were related positively for out-patient and PHR and FHR use were related positively for out-patient. 2) Revisiting: PHR use and the need of an assistant for follow-up patients were related for them and the PayTV were negatively related. Conclusion: FHR, PHR and assistant system for follow-up patient's condition were very useful factors to increase patient's loyalty.

Modification of PLA by Irradiation of Electron Beam in the Presence of Functional Monomer: Rheological and Thermal Properties (기능성 단량체를 함유한 PLA의 전자선 조사에 의한 개질: 유변학적 성질 및 열적 특성)

  • Kang, Kyoung Soo;Shin, Boo Young
    • Korean Chemical Engineering Research
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    • v.46 no.1
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    • pp.124-130
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    • 2008
  • In order to fabricate a modified poly (lactic acid) (PLA) for applications requiring high melt strength, a PLA has been irradiated in the presence of functional monomer of glycidyl methacrylate (GMA). Samples were prepared with various contents of GMA and irradiation dosages, and were characterized by observing their thermal and melt viscoelastic properties and gel faction. The complex viscosity and storage modulus of the modified PLA without GMA were lower than those of the original PLA. Those of the modified PLA decreased with increasing dosage. In the case of the modified PLA containing 0.1 phr or 0.3 phr of GMA, their changing tendency with dosage was similar to the irradiated PLA without GMA. However, the 5 kGy irradiated PLA containing 0.5 phr of GMA showed the greatly enhanced complex viscosity and storage modulus, which were about 3 and 10 times higher than those of the original PLA at a frequency of 0.1 rad/s, respectively.

Personalized diet and exercise management service based on PHR (PHR기반 개인 맞춤형 식이·운동 관리 서비스 개발)

  • Jung, Eun-Young;Jeong, Byoung-Hui;Yoon, Eun-Sil;Kim, Dong-Jin;Park, Yoon-Young;Park, Dong-Kyun
    • Journal of the Korea Society of Computer and Information
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    • v.17 no.9
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    • pp.113-125
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    • 2012
  • We developed a Smartphone application based on PHR(Personal Health Records) provided by a tertiary hospital to provide users personalized diet, exercise contents. It uses Relevance ratio algorithm of diet and excercise being correlated with diseases listed on PHR to provide personalized contents to management of individual diseases and record the amounts of food taken and exercise along with calories consumed through exercise. Besides, developed U-Health Service also considering users' conditions and conveniences, as a service to use contents and record suitable for the individuals who share the information on restaurants locations, their menus, and nutrition based on users' location information.

Kinetics of Thermal Degradation of Polypropylene/Nanoclay/Wood Flour Nanocomposites

  • Mohan, D. Jagan;Lee, Sun-Young;Kang, In-Aeh;Doh, Geum-Hyun;Park, Byung-Dae;Wu, Qinglin
    • Journal of the Korean Applied Science and Technology
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    • v.24 no.3
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    • pp.278-286
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    • 2007
  • As a part of enhancing the performance of wood-plastic composites (WPC), polypropylene (PP)/ nanoclay (NC)/ wood flour (WF) nanocomposites were prepared using melt blending and injection molding process to evaluate their thermal stability. Thermogravimetric analysis (TGA) was employed to investigate thermal degradation kinetics of the nanocomposites both dynamic and isothermal conditions. Dynamic scans of the TGA showed an increased thermal stability of the nanocomposites at moderate wood flour concentrations (up to 20 phr, percentage based on hundred percent resin) while it decreased with the addition of 30 phr wood flour. The activation energy $(E_a)$ of thermal degradation of nanocomposites increased when nanoclay was added and the concentration of wood flour increased. Different equations were used to evaluate isothermal degradation kinetics using the rate of thermal degradation of the composites, expressed as weight loss (%) from their isothermal TGA curves. Degradation occurred at faster rate in the initial stages of about 60 min., and then proceeded in a gradual manner. However, nanocomposites with wood flour of 30 phr heated at $300^{\circ}C$ showed a drastic difference in their degradation behavior, and reached almost a complete decomposition after 40 min. of the isothermal heating. The degree of decomposition was greater at higher temperatures, and the residual weight of isothermal degradation of nanocomposites greatly varied from about 10 to 90%, depending on isothermal temperatures. The isothermal degradation of nanocomposites also increased their thermal stability with the addition of 1 phr nanoclay and of wood flour up to 20 phr. But, the degradation of PP100/NC1/MAPP3/WF30 nanocomposites with 30 phr wood flour occurs at a faster rate compared to those of the others, indicating a decrease in their thermal stability.

Study on Synthesis and Adhesion Properties of Water-based Acrylic Tackifier According to the Content of Chain Transfer Agent (분자량 조절제의 함량에 따른 수계 아크릴 점착부여제의 합성 및 점착 특성 연구)

  • Baek, Lan-Ji;Jeong, Boo-Young;Kim, Se-Jin;Huh, PilHo;Cheon, Jungmi;Chun, Jae-Hwan
    • Journal of Adhesion and Interface
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    • v.23 no.3
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    • pp.80-86
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    • 2022
  • In this study, water-based acrylic tackifier with different contents of 1-dodecanethiol(n-DM), a chain transfer agent(CTA), were synthesized to improve the performance and adhesive properties of water-based acrylic pressure sensitive adhesive(PSA). In order to investigate the change in physical properties according to the amount of water-based acrylic tackifier added, 10/20/30 phr of water-based acrylic tackifier was added to the water-borne acrylic emulsion to measure the physical properties. The molecular weight and glass transition temperature(Tg) of the synthesized water-based acrylic tackifier tended to decrease as the content of n-DM increased. When a water-based acrylic tackifier was added to the water-borne acrylic emulsion, the peel strength and heat-resistance were increased. Also, when the water-based acrylic tackifiers were added at 10 phr or 20 phr, the best value was shown.

Analysis of dielectric and insulation characteristics of elastic epoxy resin according to elastomer contents for power machines (전력용 탄성형 에폭시의 유전 및 절연 특성 해석)

  • Kim, Seok-Jae;Park, Seong-Hee;Lim, Kee-Joe;Lee, Ki-Tae;Kang, Seong-Hwa;Park, Dea-Hee
    • Proceedings of the KIEE Conference
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    • 2004.11a
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    • pp.230-232
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    • 2004
  • In this paper, we investigated dielectric and insulation characteristics of epoxy resin which includes elastomers to improve mechanical property, as varied additive elastomer contents with 5[phr], 10[phr], 15[phr], and 20[phr]. We measured permittivity and tan $\delta$ at 1kHz of signal frequency and room temperature. And we also measured BVD(break-down voltage) and volume resistivities. According to the experimental results, it is appeared that when the additive elastomer contents are increasing, permittivity, volume resistivity, BVD and volume resistance are decreasing because elastomer remains inferior to epoxy resin on electrical properties.

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Properties of SBR Nanocomposites Reinforced with Organoclay/Carbon Black Dual Phase Fillers (카본 블랙/유기화 클레이로 보강된 SBR 나노 복합재료: 모폴로지와 기계적 물성)

  • Kang, B.S.;Kim, W.
    • Elastomers and Composites
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    • v.42 no.1
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    • pp.9-19
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    • 2007
  • In this study, SBR (Styrene-butadiene rubber: solid content: 25 wt%) nanocomposites reinforced with carbon/organoclay(C18-MMT) were manufactured by a latex method. The SBR nanocomposites was made with the dual phase fillers. The mixing ratios, i.e. carbon black/C18-MMT, were 50/0, 49/1, 48/2, 47/3, 45/5, 44/6, 40/10. Total filler content of compounds was restricted to 50 phr. Cure characteristics and mechanical properties of SBR nanocomposites with carbon black and C18-MMT were evaluated. The SBR nanocomposites containing 49/1 ratio of carbon black/C18-MMT showed good dispersity and excellent values of ODR torque, tensile strength, modulus and tear energy. It was found that the improvement of the mechanical properties was mainly due to the reinforcing effect, i.e., the improvement of dispersion of silicates in the rubber matrix.

A study on the oxidation characteristics of Polybutadiene & Polyisoprene containing various types of antioxidants by DSC (산화방지제(酸化防止劑)를 배합(配合)한 Polybutadiene과 Polyisoprene의 DSC에 의(依)한 산화특성(酸化特性) 연구(硏究))

  • Yoo, Chong-Sun;Choi, Seoi-Young;Paik, Nam-Chul
    • Elastomers and Composites
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    • v.18 no.4
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    • pp.140-147
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    • 1983
  • The purpose of this dissertation is to increase oxidation resistance for Polybutadiene & Polyisoprene, and to investigate the energetics of inhibited oxidation of Polybutadiene & Polyisoprene stabilized with various types of antioxidants using DSC. The results of the study are as fellows: 1. In the DSC SCREEN for the onset temperature of oxidation, Polybutadiene was faster than Polyisoprene for the samples containing no antioxidant in air. 2. In the DSC evaluation for Polybutadiene, Recipe BG-4 with 2.0phr compounds of antioxidant was the best effective, and Recipe BS-4 with 2.0phr compounds of antioxidant was the worst effective, and the degrees of effect of antioxidant were exhibited in the ranking of G-1, D, BHT, and SP, roughly. 3. In the DSC evaluation for the Polyisoprene, Recipe IG-4 with 2.0phr compounds of antioxidant was the best effective, and Recipe ID-4 with 2.0phr compounds of antioxidant was the worst effective, and the degrees of effect of antioxidant were exhibited in the ranking of G-1, SP, BHT, and D roughly. 4. In the study on enthalpy which depends on exothermal reaction, the enthalpy of Polyisoprene was gloater than that of Polybutadiene. However, the problem was not solved completely, and it needs further studies.

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