• Title, Summary, Keyword: 시차 주사 열량 분석

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A Study on the Thermochromic properties of Ti-doped Vanadium Dioxide (티타늄이 도핑된 이산화 바나듐의 열변색 특성에 관한 연구)

  • Park, Jin Wook;Park, Seong-Soo;Ahn, Byung Hyun;Hong, Seong-Soo;Lee, Gun Dae
    • Clean Technology
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    • v.21 no.4
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    • pp.235-240
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    • 2015
  • In this study, vanadium dioxide was doped with titanium (0~0.5 at %) to improve thermochromic properties. The titanium doped vanadium dioxide (Ti-VO2) particles were prepared via thermolysis process using vanadyl sulfate, ammonium bicarbonate and titianium chloride as precursors. The crystal structure, morphology, chemical bonding and thermochromic properties were investigated by using XRD, FE-SEM, XPS, DSC and UV-Vis-NIR spectroscopy. It was found that titanium was successfully doped into the crystal lattice of VO2 and the obtained Ti-VO2 particles have monoclinic structure. With increasing Ti concentration, the particle size and phase transition temperature of Ti-VO2 particles decreased and NIR switching efficiency increased.

Influences to Additive Type on Carbon Nanotube metal composite (첨가제 종류에 따른 탄소나노튜브 금속복합재료 소결코팅 영향)

  • Kim, Dea-Hea;Zheng, XI-Ru;Kim, Myin-Su;Park, Chan-Woo
    • Composites Research
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    • v.25 no.5
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    • pp.159-163
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    • 2012
  • The coating of metal surface with carbon nanotubes(CNTs) has been studied for the heat transfer enhancement of the boiling and condensation of refrigerant. The multiwalled carbon nanotube/copper oxide(CuO) composite powder, which has been surface modified by dispersant and polyvinyl alcohol solution, was ultrasonically sprayed and sintered on a copper wafer. In this paper, experiments were performed to assess the characterization and comparison of the carbon nanotube before and after sinterning and the morphology changes of the CNT/CuO-coated surface by using different dispersants. The dispersants used are THF (Tetrahydrofuran), SDBS(Dodecylbenzenesulfonic acid sodium salt), SDS(Sodium dodecy sulfate). The samples were examined by scanning electron microscopy(SEM), thermogravimetric analysis(TGA), differential scanning calorimeter(DSC) and Raman spectroscopy.

Synthesis and Characterization of New Thermotropic Liquid Crystalline Polyurethanes (새로운 형태의 액정폴리우레탄의 합성 및 특성)

  • Lee, Jong-Baek;Lee, Kwang-Hyun;Kang, Byung-Chul
    • Elastomers and Composites
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    • v.41 no.2
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    • pp.108-115
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    • 2006
  • A series of thermotropic polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, 1,4-phenylene diisocyanate, and hexamethylene diisocyanate with 4,4'-Bis(9-hydroxynonoxy)biphenyl (BP9). 4,4'-bis(9-hydroxynonoxy)biphenyl exhibited a smectic type mesophase. Mesophase was found for all synthesized liquid crystalline polyurethanes except 1,4-PDI/BP9 based polyurethane. Structures of the monomer and the corresponding polymers were identified using FT-IR and $^1H-NMR$ spectroscopies. Their phase transition temperatures and thermal stability were also investigated by differential scanning calorimetry and optical polarizing microscopy.

Study on Type of Different Polyols for Physical Properties of Polyurethane Foam Under Sea Water (해수에서 폴리올 종류가 폴리우레탄 폼의 물성에 미치는 영향)

  • Kim, Sang-Bum
    • Elastomers and Composites
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    • v.46 no.2
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    • pp.158-163
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    • 2011
  • Rigid polyurethane foam (PUF) was synthesized with different contents of aliphatic polyester polyol, aromatic polyester polyol and aliphatic polyether polyol to know change of properties under sea water. UTM(universal testing machine), DSC(differential scanning calorimetry), hardness meter and FT-IR(Fourier transform spectroscopy) were used to study the PUF`s physical properties under sea water. Compressive strength and hardness of PUF decreased with increasing the content of aromatic polyester polyol under sea water as aging. According to the results of IR spectral analysis, reduction of urethane and urea peak was found and allophanate and biuret peak increased. Although glass transition temperature of PUF increased, mechanical properties of PUF decreased under sea water, because PUF gets brittle when crosslink density increase.

Investigation for the physio-chemical stabilities of Idebenone encapsulated with non-hydrous skin analogue membrane and its transdermal penetration

  • Jeong, Kwan-Young;Lee, Dong-Kyu
    • Journal of the Korean Applied Science and Technology
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    • v.25 no.3
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    • pp.313-321
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    • 2008
  • 오래전부터, 많은 여성들은 자신들의 젊음을 연장하고, 외모를 더 아름답게 가꾸고, 이를 죽을 때까지 유지하는 것을 바래왔다. 이에 의사와 약사들뿐만 아니라, 많은 화장품 연구자들도 노화와 관련된 기술개발에 총력을 기울여 왔다. 따라서, 이들 연구자들은 노화방지를 위한 새로운 원료를 찾고, 이를 안정화하고, 피부로 전달하는 기술개발에 항상 관심을 쏟아왔다. 뛰어난 노화방지 화장품 개발을 위해서, Ubiquinone의 일종인 ldebenone에 대해 연구하였고, 이를 비수계 피부유사막 기술을 가지고 캡슐화하고 약물전달하는 연구를 진행하였다. 먼저, 편광현미경(PM, Polarized Microscope), X-선 회절분석(XRD, X-ray Diffractions) 및 시차주사열량계 (DSC, Differential Scanning Calorimetry)를 이용하여 Idebenone을 담지한 피부유사막 액정을 비수계 조건에서 구조 및 열적특성을 조사하였다. 그 결과 비수계 조건에서도 규칙적으로 패킹(Packing)된 지질이중층(Lipid bilayer)과 용매의 연속층으로 이루어진 고밀집된 라멜라(Lamella) 구조의 형성유무와 이때의 상거동을 확인할 수 있었다. 결론적으로 높은 극성도로인해 물분자와 접촉하면 불안정해지는 경향이 있는 Idebenone을 비수계 조건에서 각질층(SC, Stratum Corneum)과 구조 및 조성이 유사한 피부유사막을 디자인하여 안정하게 캡슐화 하였다. 이를 적용한 화장품은 모든 보관조건에서 유화입자의 안정성을 유지함을 확인하였고, Idebenone의 활성역가 또한 $40^{\circ}C$에서 6개월 동안 약 90%이상을 유지하는 우수한 결과를 나타냈다.

Microstructure and Thermal Characteristics of Bio-based Terpolymer Made from Terephthalic Acid with Ethylene Glycol, 1,4-Cyclohexane Dimethanol, and Isosorbide (Ethylene Glycol, 1,4-Cyclohexane Dimethanol, Isosorbide와 Terephthalic Acid로 제조되는 바이오기반 삼원공중합체의 미세구조 및 열적 특성)

  • Lee, Sangmook;Kim, Sungki;Hong, In-Kwon
    • Polymer Korea
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    • v.39 no.2
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    • pp.287-292
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    • 2015
  • Characterization of a series of bio-based terpolymers containing various amounts of ethylene glycol, 1,4-cyclohexylene dimethanol, and isosorbide units were studied by $^1H$ NMR and $^{13}C$ NMR. The NMR results revealed that they had all random microstructures and that their sequence distribution was affected by the content of isosorbide. From DSC data for the terpolymer series investigated, it was observed that the glass transition temperature increased mainly as the content of isosorbide increased. The glass transition temperatures of terpolymers were estimated from the composition by extended Fox equation.

Thermal Analysis of Nickel-Base Superalloys by Differential Scanning Calorimetry (시차주사열량측정법에 의한 니켈기 초내열 합금의 열분석)

  • Yun, Jihyeon;Oh, Junhyeob;Kim, Hongkyu;Yun, Jondo
    • Korean Journal of Materials Research
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    • v.26 no.5
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    • pp.235-240
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    • 2016
  • Appropriate thermo-mechanical properties of nickel-based superalloys are achieved by heat treatment, which induces precipitation and solid solution hardening; thus, information on the temperature ranges of precipitation and dissolution of the precipitates is essential for the determination of the heat treatment condition. In this study, thermal analyses of nickel-based superalloys were performed by differential scanning calorimetry method under conditions of various heating rates of 5, 10, 20, or 40K/min in a temperature range of 298~1573K. Precipitation and dissolution temperatures were determined by measuring peak temperatures, constructing trend lines, and extrapolating those lines to the zero heating rate to find the exact temperature under isothermal condition. Determined temperatures for the precipitation reactions were 813, 952, and 1062K. Determined onset, peak, and offset temperatures of the first dissolution reaction were 1302, 1388, and 1406K, respectively, and those values of the second dissolution reaction were 1405, 1414, and 1462K. Determined solvus temperature was 1462K. The study showed that it was possible to use a simple method to obtain accurate phase transition temperatures under isothermal condition.

Aging of Solid Fuels Composed of Zr and ZrNi Part 2: Kinetics Extraction for Full Simulation (Zr과 ZrNi로 구성된 고체연료의 노화 연구 Part 2: 화학반응식 추출 및 성능모사)

  • Han, Byungheon;Park, Yoonsik;Gnanaprakash, K.;Yoo, Jaeyong;Yoh, Jai-ick
    • Journal of the Korean Society of Propulsion Engineers
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    • v.24 no.2
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    • pp.14-27
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    • 2020
  • Differential scanning calorimetry and numerical analysis were performed to estimate the performance degradation and ignition characteristics of the pyrotechnic device due to aging. The reaction kinetics extracted from the calorimetry are implemented into the numerical simulation of the igniter and the pyrotechnic delay, subjected to natural, thermal, and hygrothermal aging conditions. Also, combustion experiments are conducted to confirm that aging due to moisture is a major cause of performance failure of the pyrotechnic device as shown from the present numerical simulations.

Preparation and Characterization of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/Graphene Nanocomposites (3-히드록시부티레이트-3-히드록시발러레이트 공중합체/그래핀 나노복합체의 제조 및 물성)

  • You, Eun Jung;Lee, Dan Bi;Ha, Chang-Sik
    • Journal of Adhesion and Interface
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    • v.16 no.3
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    • pp.108-115
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    • 2015
  • In the present work, we investigated poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/graphene nanocomposites. The electrical, hydrophobic properties and thermal properties of the nanocomposite films having different graphene contents were investigated. The scanning electron microscopy (SEM) morphology showed good dispersion of graphene layers in the PHBV matrix. Based on the X-ray diffraction and differential scanning calorimetry, the addition of graphene increased the crystallinity of PHBV. Thermal stability, hydrophobicity, and electrical conductivity of the nanocomposites were increased with increasing the graphene contents.

Study on the Thermal Characteristic Comparison of Fire.Explosion Hazard of Fugitive Dust Generated in the Manufacturing Process (제조공정상 발생하는 비산분진의 화재·폭발 위험성에 대한 열적특성 비교에 관한 연구)

  • Sun, Ko Jae
    • Journal of the Society of Disaster Information
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    • v.10 no.1
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    • pp.71-83
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    • 2014
  • This study carried out an experiment in order to compare thermal characteristics after collecting dust generated in the process of disposing of waste tire, plywood flour in the process of manufacturing plywood, salicylic acid dust in the process of manufacturing functional soap, and dust in the process of manufacturing wheat powder, which has potential fire and explosion hazard. According to the results of experiment, the analysis showed that all samples subject to the experiment were in the condition where heat flux decreased and temperature decreased as the quantity of added talc was increased. This shows that decomposition rate decreased, and hazard decreased. However, in all of samples subject to the experiment, as heating rate increased, endothermic onset temperature moved to the low-temperature part, and the amount of absorbed heat was largely increased. This showed that the decomposition hazard of sample increased as heating rate increased, according to the analysis. Besides, TGA experiment results showed that thermal stability was secured because total weight loss decreased as the amount of talc was increased for all samples subject to the experiment regarding the ratio of weight loss. It is expected that the continuous research and supplementation of dust explosion mechanism in the future will contribute to the establishment of measures for the effective dust explosion prevention.