• Title, Summary, Keyword: NMA

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Water Resistance and Thermal Properties of Resin Based on Silane-modified Vinyl Acetate-Acrylic Emulsion Copolymers (실리콘 수식 비닐아세테이트-아크릴 공중합체 수지의 방수성 및 열적 성질)

  • Naghash, Hamid Javaherian
    • Polymer Korea
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    • v.34 no.4
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    • pp.306-312
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    • 2010
  • Triphenylvinylsilane (TPVS) containing vinyl acetate (VAc), butyl acrylate (BA), and Nmethylolacrylamide (NMA) copolymers were prepared by emulsion polymerization. The polymerization was performed at $80^{\circ}C$ in the presence of auxiliary agents and ammonium peroxodisulfate (APS) as the initiator. Sodium dodecyl sulphate (SDS) and Arkupal N-300 were used as anionic and nonionic emulsifiers, respectively. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and dynamic light scattering (DLS). Thermal properties of the copolymers were studied by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology of copolymers was also investigated by scanning electron microscopy (SEM) and then the effects of silicone concentrations on the properties of the TPVS-containing VAc-acrylic emulsion copolymers were discussed. The obtained copolymers have high solid content (50%) and can be used in weather resistant emulsion paints as a binder.

Status of Development of Pyroprocessing Safeguards at KAERI (한국원자력연구원 파이로 안전조치 기술개발 현황)

  • Park, Se-Hwan;Ahn, Seong-Kyu;Chang, Hong Lae;Han, Bo Young;Kim, Bong Young;Kim, Dongseon;Kim, Ho-Dong;Lee, Chaehun;Oh, Jong-Myeong;Seo, Hee;Shin, Hee-Sung;Won, Byung-Hee;Ku, Jeong-Hoe
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.15 no.3
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    • pp.191-197
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    • 2017
  • The Korea Atomic Energy Research Institute (KAERI) has developed a safeguards technology for pyroprocessing based on the Safeguards-By-Design (SBD) concept. KAERI took part in a Member-State Support Program (MSSP) to establish a pyroprocessing safeguards approach. A Reference Engineering-scale Pyroprocessing Facility (REPF) concept was designed on which KAERI developed its safeguards system. Recently the REPF is being upgraded to the REPF+, a scaled-up facility. For assessment of the nuclear-material accountancy (NMA) system, KAERI has developed a simulation program named Pyroprocessing Material Flow and MUF Uncertainty Simulation (PYMUS). The PYMUS is currently being upgraded to include a Near-Real-Time Accountancy (NRTA) statistical analysis function. The Advanced Spent Fuel Conditioning Process Safeguards Neutron Counter (ASNC) has been updated as Non-Destructive Assay (NDA) equipment for input-material accountancy, and a Hybrid Induced-fission-based Pu-Accounting Instrument (HIPAI) has been developed for the NMA of uranium/transuranic (U/TRU) ingots. Currently, performance testing of Compton-suppressed Gamma-ray measurement, Laser-Induced Breakdown Spectroscopy (LIBS), and homogenization sampling are underway. These efforts will provide an essential basis for the realization of an advanced nuclear-fuel cycle in the ROK.

A Study on Exothermic Properties of TiO2/Epoxy Nanocomposites (TiO2/Epoxy 나노복합재의 발열 특성에 관한 연구)

  • Ahn, Seok-Hwan;Ha, Yoo-Sung;Moon, Chang-Kwon
    • Journal of Ocean Engineering and Technology
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    • v.27 no.5
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    • pp.99-104
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    • 2013
  • Recently, various nanoparticles have been used for filler in polymer matrices. The particles of nano size are whether high or not cross-link density in polymer affects the thermal and mechanical properties of one. The properties change as a result of chemical reactions between the nanoparticles and the surface of the polymer. There are two models for nanocomposites: "repulsive interaction" and "attractive interaction" between the nanoparticles and matrix. In this study, the variation in the curing mechanism was examined when nano-size $TiO_2$ was dispersed into an epoxy (Bisphenol A, YD-128) with different curing agents. The results of this study showed that the exothermic temperature and Tg in the case of the nanoparticles used (Jeffamine) (D-180) at room temperature were reduced by an increase in the $TiO_2$ contents because of the "repulsive interaction" between the nanoparticles and the matrix. The tensile strengths were increased by increasing amounts of $TiO_2$ until 3 wt% because of a dispersion strengthening effect caused by the nanoparticles, because of the repulsive interaction. However, such tensile properties decreased at 5 wt% of $TiO_2$, because the $TiO_2$ was agglomerated in the epoxy. In contrast, in the case of the nanoparticles that used NMA and BDMA, the exothermic temperature and Tg tended to rise with increasing amounts of $TiO_2$ as a result of the "attractive interaction." This was because the same amounts of $TiO_2$ were well dispersed in the epoxy. The tensile strength decreased with an increase in the $TiO_2$ contents. In the general attractive interaction model, however, the cross-link density was higher, and tensile strength tended to increase. Therefore, for the nanoparticles that used NMA, it was difficult to conclude that the result was caused by the "attractive model."

Color Strength and Fastness of Pigment Ink with Various Binder Monomer Compositions (바인더의 공중합체 조성에 따른 안료잉크의 발색성 및 견뢰도 연구)

  • Kwon, Woong;Lee, Minkyu;Jeong, Euigyung;Bae, Jin-Seok
    • Textile Coloration and Finishing
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    • v.30 no.4
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    • pp.256-263
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    • 2018
  • The binder polymers for digital textile printing(DTP) pigment inks were prepared using miniemulsion polymerization with various monomer compositions to study effects of monomer compositions on particle size distribution, average molecular weight, Tg, and color strength and rubbing fastness of the dyed fabrics with the prepared binder based pigment ink. The monomers used were MMA(Methyl methacrylate), BA(Butyl acrylate), MAA(Methacrylic acid), NMA(N-methylol acrylamide), NEA(N-ethylol acrylamide) and the ratios of the monomers were changed. The particle size was the smallest with 136nm when the MMA to BA weight ratio was 4:16 and the largest with 290nm when the MMA, BA, MAA, NEA ratio was 2.5:17:0.25:0.25. However, the glass transition temperature was lowest with $-41.90^{\circ}C$ and the color strength and rubbing fastness of the resulting sample were the best when the MMA, BA, MAA, NEA ratio was used. This suggested that the introduction of the NEA monomer to the binder polymer for the pigment ink could be an efficient way to enhance the rubbing fastness of the DTP pigment inks present.

Crystal and Magnetic Properties of 57Fe Doped MnAs for Magnetic Refrigeration Application

  • Lim, Jung Tae;Cho, Hyun Tae;Kim, Sam Jin;Kim, Chul Sung;Lee, Young Bae
    • Journal of the Korean Physical Society
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    • v.71 no.9
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    • pp.575-578
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    • 2017
  • The $Mn_{1-x}{^{57}}Fe_xAs$ (x = 0.001, 0.003, 0.005) compounds for magnetic refrigeration application were synthesized by using a solid-vapor reaction method. We have investigated the crystallographic and magnetic properties of $Mn_{1-x}{^{57}}Fe_xAs$ (x = 0.001, 0.003, 0.005) samples by using x-ray diffractometer (XRD), vibrating sample magnetometer (VSM), superconducting quantum interference device (SQUID), and $M{\ddot{o}}ssbauer$ spectrometer. The XRD patterns, revealed that all samples exhibited hexagonal space group $P_{63}/mmc$ below Curie temperature ($T_C$), while above $T_C$ they belong to the orthorhombic space group P nma. The temperature-dependent magnetization curves under 200 Oe between 4.2 and 320 K showed a large hysteresis in the magnetization as a function of the temperature. To analyze the meagnetocaloric effect, the value of magnetic entropy ($-{\Delta}S_M$) was calculated from the isothermal initial curves up to 5 T at various temperatures. $M{\ddot{o}}ssbauer$ spectra of $Mn_{0.997}{^{57}}Fe_{0.003}As$ sample were taken at various temperatures ranging from 4.2 to 315 K.

Effect of Korea Red Ginseng Extract on PC12 Cell Death Induced by Serum Deprivation (홍삼 수용성 추출물이 PC12 세포사멸에 미치는 영향)

  • Lee, Sang-Hyun;Yun, Young-Gab
    • Journal of Korean Medicine Rehabilitation
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    • v.19 no.2
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    • pp.103-112
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    • 2009
  • Objectives : This study was to evaluate the pharmacological effect of Korea Red Ginseng aqueous extract (KRGE) on serum-deprived apoptosis of neuronal-like pheochromocytoma PC12 cells and to investigate its underlying action mechanism. Methods : KRGE was prepared by extracting Korea Red Ginseng with hot water and concentrating using a vacuum evaporator. Cell viability was determined after incubation of cells with KRGE or chemical inhibitor in serum-deprived medium for 60 h by counting intact nuclei following lysing of the cell membrane. Caspase activities were measured using chromogenic substrates and signal-associated protein phosphorylation and cytochrome c release were determined by Western blot analyses using their specific antibodies. Results : Serum deprivation induced PC12 cell death, which was accompanied by typical morphological features of apoptotic cell, such as nuclear fragmentation, caspase-3 activation, and cytochrome c release. This apoptotic cell death was significantly inhibited by KRGE and caspase-3 inhibitor, but not by the addition of NMA, ODQ, and PD98059. KRGE promoted phosphorylation of Akt and Bad, and this phosphorylation was inhibited by the PI3K inhibitor LY92004. In addition, this inhibitor also reversed KRGE-mediated protection of PC 12 cells from serum deprivation. These results suggested that KRGE protects PC12 cells from serum deprivation-induced apoptosis through the activation of PI3K/Akt-dependent Bad phosphorylation and cytochrome c release, resulting in caspase-3 activation. Conclusions : KRGE should be considered as a potential therapeutic drug for brain diseases including stroke induced by apoptosis of neuronal cells.

A Study on the Design of Network Management Architecture based on TMN Concept (TMN 개념을 응용한 통신망 관리구조 설계에 관한 연구)

  • 김영명;조영현
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.1
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    • pp.170-182
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    • 1994
  • With the evolution of telecommunications network, the operational enviroments of a morden telecommunication network are becoming more complex and diverse. Therefore. the design of NMA( Network Management Aechitecture) that pursues standardization and openness in order to accommodatae them actively will be required. In such a network environment which composes various and heterogeneous network elements, it is not easy to surpport efficiently TMN MSs(Management Services) because it has lack of interoperability among them. This paper proposes a top-down approach being taken to design a network management architecture with establishing the hierarchical relationships of management services based on ITU-TS(Telecommunication Standardization in Europe) TMN concept, and allocating MSC(Management Service Component) by TMN management layer, and analyzing the information flow between FAs(Functional Areas).

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Angiogenic Effects of Korea Red Ginseng Water Extract in the In Vitro and In Vivo Models (홍삼수용성추출물이 혈관신생에 미치는 영향)

  • Rho, Euy-Joon;Ryu, Seong-Hun;Kim, Gyu-Min;Lee, Sang-Hyun;Yun, Young-Gab
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.23 no.2
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    • pp.416-425
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    • 2009
  • Angiogenesis is important for promoting cardiovascular disease, wound healing, and tissue regeneration. We here investigated the pharmacological effects of Korea red ginseng water extract (KRGE) on angiogenesis and its underlying signal mechanism. This study showed that KRGE increased in vitro proliferation, migration, and tube formation of human umbilical endothelial cells, as well as stimulated in vivo angiogenesis. KRGE-induced angiogenesis was accompanied by phosphorylation of ERK1/2, Akt, and endothelial nitric oxide synthase (eNOS) as well as an increase in NO production. Inhibition of PI3K activity by wortmannin completely inhibited KRGE-induced angiogenesis and phosphorylation of Akt, ERK1/2, and eNOS, indicating that PI3K/Akt activation is an upstream event of KRGE-mediated angiogenic pathway. The MEK inhibitor PD98059 completely blocked KRGE-induced angiogenesis and ERK phosphorylation without affecting Akt and eNOS activation. However, the eNOS inhibitor NMA effectively inhibited tube formation, but partially blocked proliferation and migration as well as ERK phosphorylation without altering Akt and eNOS activation, revealing that eNOS/NO pathway is in part involved in ERK1/2 activation. This study first demonstrated the critical involvement of both ERK1/2 and eNOS activation in KRGE-induced angiogenesis, which lie on downstream of PI3K/Akt. Thus, these results indicate that KRGE requires activation of both the PI3K/Akt-dependent ERK1/2 and eNOS signal pathways and their cross-talk for its full angiogenic activity.

Structural characterization of $LaTi_{0.8}V_{0.2}O_3$ compounds by transmission electron microscoy (투과전자현미경에 의한 $LaTi_{0.8}V_{0.2}O_3$ 화합물의 결정구조 분석)

  • 김좌연;윤의중;박경순;심규환;류선윤;김유혁
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.4
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    • pp.567-572
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    • 1998
  • The crystalline structure of $LaTi_{0.8}V_{0.2}O_3$ solid solutions, prepared by arc-melting palletized mixtures of predried $La_2O_3,\;V_2O_3,\;TiO_2$, and Ti, was investigated by transmission electron microscopy and computer image simulation. Computer image simulations were performed by the multislice method for a wide range of sample thickness and defocusing value. The structure of $LaTi_{0.8}V_{0.2}O_3$ was determined as a $GdFeO_3$-type orthorhombic $(a\approx5.58{\AA},\;b\approx7.89{\AA},\;and\;c\approx5.58{\AA})$ with a space group $P_{nma-}$. No evidence of ordering of Ti and V atoms in $SaTi_{0.8}V_{0.2}O_3$ was found.

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Permeability Variation With Lift Thickness of Asphalt Pavement (아스팔트 포장의 시공 포설두께에 따른 투수계수 변화특성)

  • Park, Sang Hyun;Moon, Jun Ho;Bae, Seok Il;Kim, Young Uk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.3
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    • pp.2229-2233
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    • 2015
  • The permeability of HMA(hot mixed asphalt) is a major influencing factor for long-term performance of the pavement. Especially, the lift thickness of the pavement during construction causes a wide range of physical properties of HMA. This study investigates the correlationship between the lift thickness and the physical properties of HMA through a series of laboratory experiments. The specimens were cored from a construction site of the dense graded asphalt pavement. The cored samples have various lift thickness and the number of compaction for the study. The results of the study show that the permeability of the sample decreases with the apperant density and t/NMAS, and the air void ratio. Therefore, the commonly used construction method as a constant lift thickness regardless of conditions needs to be reconsidered.