• Title/Summary/Keyword: 열분석적 특성

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Preparation and Characterization of Cellulose Acetate/Poly Ethylene Glycol Blend Having High Melt Processibility (우수한 용융특성을 갖는 Cellulose acetate/Poly ethylene glycol 조성물의 제조 및 특성 해석)

  • Lee, Hae Sung;Lee, Sung Jun;Jung, Sang Won;Kim, Hyun-Chul;Kim, Eunjoo;Go, Young Jun;Lee, Se Guen
    • Journal of Korean Ophthalmic Optics Society
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    • v.17 no.1
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    • pp.1-10
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    • 2012
  • Purpose: Cellulose acetate (CA) was blended with polyethyleneglycol (PEG) having different molecular weight at various mixing conditions to enhance melt-processibility of CA, which might prevent the harmful effect resulted from the introduction of phthalic plasticizer. Methods: To establish optimal plasticizing conditions, CA/PEG blends were examined under various plasticizing conditions: PEG concentration, molecular weight of PEG, and plasticzing temperature. Mechanical properties of the CA/PEG blends, as well as migration and exudation of the PEG, were performed in order to evaluate the efficiency of plasticization. Results: Compared to industrial CA resin plasticized by diethyl phthalate, CA/PEG blends exhibited similar thermal plasticization. It was established that the optimum condition was to blend 30~40 phr PEG with molecular weight 400 at $175{\sim}180^{\circ}C$. CA/PEG blend showed superior glassness, PEG stability, and mechanical properties. Conclusions: CA/PEG blends would be a eco-friendly glasses frame to substitute traditional CA glasses frame prepared phthalate plasticizers.

Characteristics Variation of the Sedimentary Environment in Winter Season around the Baramarae Beach of Anmyeondo Using Surface Sediment Analysis (표층퇴적물 분석을 통한 동계 안면도 바람아래해수욕장 주변의 퇴적환경 변화특성)

  • JANG, Dong-Ho;KIM, Jang-Soo;PARK, No-Wook
    • Journal of The Geomorphological Association of Korea
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    • v.17 no.1
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    • pp.15-27
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    • 2010
  • This study investigated the sedimentary environment changes in the Baramarae beach of Anmyeondo through spatio-temporal surface sediment analysis. In the winter season 2009, surface sediments were classified into 7 sedimentary facies such as gravel, sand, gravelly sand, gravelly muddy sand, muddy sand, silty sand, and sandy silt. Time-series analysis of average grain size from 2002 to 2009 revealed that the average grain size of sediments became finer and sorting was much worse. On the contrary, during the same period, the grain size became coarsening-trend and sorting was much better in beach area. These different grain size patterns resulted from the different change characteristics of beach and tidal flats. The southwestern beach area was connected to the open sea and thus fine sediments were removed by the environments with relatively high-energy. The sedimentation of fine sediments in the bay resulted from the tidal current action and the reduction of energy by the topographic effects. Fine sediments in the outer part of southwestern tidal flats could be explained such that the Seomot isle blocked ocean waves and as a result, low-energy environments accelerated sedimentations of fine sediments.

Study on Decay Characteristics Change of Spent Fuel Materials by DUPIC Fuel Cycle (DUPIC핵연료주기에 의한 사용 후 경수로핵연료의 방사선적 특성변화 분석)

  • Choi, Jong-Won;Ko, Won-Il;Lee, Jae-Sol;Park, Hyun-Soo
    • Journal of Radiation Protection and Research
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    • v.21 no.1
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    • pp.27-39
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    • 1996
  • The change in spent fuel characteristics by DUPIC fuel cycle(burnup of spent PWR fuel again in CANDU) is examined with time elapse since discharge. Major characteristics examined include isotopic concentration, radioactivity, decay heat radiotoxicity and radiation source-term of spent fuel material, which is existing in a type of spent PWR and DUPIC fuel. Behaviors of major nuclides contributing to such changes are also analyzed in terms of radionuclide concentration. From the analysis, the change in radionuclide concentration by DUPIC shows approximately 2% decrease in actinides concentration and 20% increase in fission products concentration. Radioactivity and decay heat of spent DUPIC fuel does not depend upon radionuclides concentrations, which is a unique in sence of general characteristics of spent fuel. In terms of gamma spectrum, spent DUPIC fuel shows lower values than that of spent PWR fuel by 40 to 50% in the range of $0.01{\sim}0.575$ MeV but much higher over 3.5MeV. Neutron Intensities of both spent fuels are mainly determined by $({\alpha},\;n)$ reaction and spontaneous fission reaction of actinides. Of them, especially, the spontaneous fission reaction Is a major neutron source-term, which causes that neutron intensities of spent DUPIC fuel $having{\sim}3.3$ times higher Cm-244 concentration are ${\sim}4$ times higher than that of spent PWR fuel.

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Effect on Graphene Addition on Characteristics of Polypropylene Biocomposites Reinforced with Sulfuric Acid Treated Green Algae (황산처리된 녹조류 보강 폴리프로필렌 바이오복합재료에 대한 그래핀 첨가영향)

  • Jang, Young Hun;Han, Seong Ok;Kim, Hyung-Il;Sim, I Na
    • Polymer(Korea)
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    • v.37 no.4
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    • pp.518-525
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    • 2013
  • To improve the mechanical properties of polypropylene (PP) biocomposites reinforced with sulfuric acidtreated green algae (SGA), SGA/graphite nanoplatelets (GNP)/PP biocomposites were prepared and their properties were evaluated depending on the particle size and content of GNP. The flexural and impact strength of SGA/GNP/PP biocomposites decreased with the addition of GNP, whereas the flexrual and storage moduli were greatly improved with increasing GNP loading. SGA/GNP/PP biocomposites reinforced with GNP5 showed generally better mechanical properties compared to that reinforced with GNP15 mainly due to the improved dispersion of the smaller GNP. SGA/GNP/PP biocomposites reinforced with GNP5 showed a lower resistance to the thermal expansion because the relatively uniform dispersion of smaller GNP was responsible for the effective heat transfer to the polymer matrix. As a result, SGA/GNP/PP biocomposite was acceptable for the general purpose application due to the improved flexural resistance, storage moduli, and damping characteristics.

Changes in the Optical and Thermal Properties of Low-Temperature Cured Polyimide Thin Films Using the Catalyst (촉매를 이용한 저온경화 폴리이미드 박막의 광학적/열적 특성 변화)

  • Park, Myeong-Soon;Kim, Kwang-In;Nam, Ki-Ho;Han, Haksoo
    • Applied Chemistry for Engineering
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    • v.24 no.3
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    • pp.320-326
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    • 2013
  • In this study, various polyimide films were synthesized via low temperature cure in order to understand changes in their physical properties when using 4,4'-oxydianiline (ODA) as a diamine and dianhydride molecules with different backbones on a single diamine such as 4,4'-Oxydiphthalic anhydride (ODPA), 4,4-hexafluoroisopropylidene diphthalic dianhydride (6FDA), and 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA). After the synthesis of poly(amic acid), polyimide films were fabricated by adding 1,4-diazabicyclo [2.2.2]octane (DABCO), a low-temperature catalyst, at various wt% to poly(amic acid)s. Changes of optical and thermal properties were compared and analyzed between polyimide films without catalyst and polyimide films with catalyst by FT-IR, UV-Vis transmittance, DSC/TGA, and WAXD analysis. Wide-angle X-ray diffraction (WAXD) analysis revealed that the mean intermolecular distance decreased with the use of a catalyst by the type of dianhydride. Thus, while the optical properties of the films improve by a low-temperature cure performed using a catalyst, their thermal properties decrease. These changes can be explained by the changes in the morphological structure of the films triggered by a catalyst-induced reduction in the mean intermolecular distance. Moreover, the results show that the type of dianhydride determines the degree of change in the optical and thermal properties in each types of polyimide, demonstrating that changes in the optical and thermal properties are directly associated with the backbone of the polyimide structure.

Analysis of Development Characteristics of the Terra Nova Bay Polynya in East Antarctica by Using SAR and Optical Images (SAR와 광학 영상을 이용한 동남극 Terra Nova Bay 폴리냐의 발달 특성 분석)

  • Kim, Jinyeong;Kim, Sanghee;Han, Hyangsun
    • Korean Journal of Remote Sensing
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    • v.38 no.6_1
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    • pp.1245-1255
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    • 2022
  • Terra Nova Bay polynya (TNBP) is a representative coastal polynya in East Antarctica, which is formed by strong katabatic winds. As the TNBP is one of the major sea ice factory in East Antarctica and has a great impact on regional ocean circulation and surrounding marine ecosystem, it is very important to analyze its area change and development characteristics. In this study, we detected the TNBP from synthetic aperture radar (SAR) and optical images obtained from April 2007 to April 2022 by visually analyzing the stripes caused by the Langmuir circulation effect and the boundary between the polynya and surrounding sea ice. Then, we analyzed the area change and development characteristics of the TNBP. The TNBP occurred frequently but in a small size during the Antarctic winter (April-July) when strong katabatic winds blow, whereas it developed in a large size in March and November when sea ice thickness is thin. The 12-hour mean wind speed before the satellite observations showed a correlation coefficient of 0.577 with the TNBP area. This represents that wind has a significant effect on the formation of TNBP, and that other environmental factors might also affect its development process. The direction of TNBP expansion was predominantly determined by the wind direction and was partially influenced by the local ocean current. The results of this study suggest that the influences of environmental factors related to wind, sea ice, ocean, and atmosphere should be analyzed in combination to identify the development characteristics of TNBP.

An Experimental Study on the Mechanical Properties of High Density Concrete Using Magnetite Aggregate (자철광 골재를 이용하는 철근콘크리트의 역학적 특성에 관한 관험적 연구)

  • 반호용;한천구;김을용
    • Magazine of the Korea Concrete Institute
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    • v.2 no.3
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    • pp.81-88
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    • 1990
  • For the protectioon of radioactive leakage, the quality control of main concrete structure in nuclear power plants is very important. So, this studey is designed to analyze the influence of kind of cement and aggregate on the mechanical properties of high density concrete. Test results of this study are as follows; 1)The slump of magnetite aggregate concrete(MAC) is found half value of nat.ural aggregate concrete (NAC). 2)As the effect of cement, the compressive strength of concrete using moderate heat cement is found higher 5-19 % than that of ordinary portland cement. 3)As the effect of fine aggregate, t.he compressive strength of MAC is found higher than that. of NAC below 340kg/$cm^2$ and lower t.han NAC above 340kg/$cm^2$. 4)As the effect of coarse aggregate, the compressive strength of MAC is found higher 17-22% than that of NAC.

Effects of PEO Additions on the Mechanical and Thermal Proprieties of PLA/PBAT Blends (폴리에틸렌옥사이드가 PLA/PBAT 블렌드 물성에 미치는 영향)

  • Jang, Hyunho;Kwon, Sangwoo;Eom, Yoojun;Yoo, Seungwoo;Park, Su-il
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.26 no.2
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    • pp.93-98
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    • 2020
  • The blends of Poly(lactic acid) (PLA) and Poly(butylene adipate-co-terephthalate) (PBAT) have been recognized as a replacement for commodity plastic films and bags in biodegradable packaging industries. The purpose of this study is to identify changes in the thermal and mechanical properties of PLA/PBAT blends with the addition of poly(ethylene oxide)(PEO). PLA (80%) and PBAT (20%) were melt mixed with 0 to 10 phr of PEO and processed using a hot press. The addition of PEO into PLA/PBAT increased the elongation at break and improved thermal stability. With PEO addition, two melting temperature (Tm) peaks of PLA/PBAT merged into one peak showing improved miscibility. The result of this study showed that the addition of PEO increased the ductility and thermal stability of PLA/PBAT blends.

Geological Characteristics of a Wetland in Mt. Geumjeong (금정산 산지습지의 지질학적 특성)

  • Cha, Eun-Jee;Hamm, Se-Yeong;Kim, Hyun-Ji;Lee, Jeong-Hwan;Cheong, Jae-Yeol;Ok, Soon-Il
    • Journal of Wetlands Research
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    • v.12 no.2
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    • pp.1-12
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    • 2010
  • This study examined geological characteristics of a wetland in Mountain Geumjeong in Busan Metropolitan City. Field survey and laboratory tests were performed to identify topographic features, geological and structural geological characteristics, rock strength along the distance from the wetland, soil profile in the wetland, and chemical property of the wetland soil. The bedrock of the wetland consists of hornblende granite. Hornblende granite and rhyolitic rock around the wetland have the joints with strikes of N-S, E-W, and NE-SW directions and with higher dips greater than $60^{\circ}$. Lower rock strength and higher weathering grades take place towards the wetlands. According to X-ray diffraction analysis of wetland soil samples, kaolinite, montmorillonite, and gibbsite appear which demonstrate weathered products of feldspars in the hornblende granite. The soil profile in the wetland comprises O, A, B, and C horizons from the land surface. The contents of the organic matters decrease from shallow parts to deeper parts of the soil profile. In addition, $K^+$ and $Na^+$ originating from the weathering of feldspars are dominant components among inorganic ions in the wetland soil.

Analysis of Urban Surface Temperature Distribution Properties Using Spatial Information Technologies (공간정보기술을 활용한 도시지역 지표온도 분포 특성 해석)

  • Lee Kwang-Jae;Jo Myung-Hee
    • Korean Journal of Remote Sensing
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    • v.20 no.6
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    • pp.397-408
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    • 2004
  • In this study, surface temperature which was extracted from Landsat TM band 6 was compared and analyzed with the AWS(Automatic Weather System) observation data for studying urban heat environment properties with possibility of remote sensing data application. In order to verification of the distribution properties of urban surface temperature, correlation analysis between surface temperature and NDVI, the distribution properties of urban surface temperature by land use/cover patterns were carried out by GIS spatial analysis techniques. The results presented that the spatial distribution of urban surface temperature was very different depending on various land use/cover patterns of surrounding areas. Also there was the reverse linear relationship between surface temperature and NDVI. These results will be worked as one of the major factors for environmentally sustainable urban planning considering the characteristics of weather environments in the near future.