• 한국표면공학회지
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• 제55권6호
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• pp.383-389
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• 2022

Natural(outdoor) and accelerated(artificial) weathering tests were performed to investigate their influence on polycarbonate. The polycarbonate materials were prepared of various formulations divided into three batches, with existing, development materials1, development materials2, containing mixture of UV additives. Weathering tests were carried out as outdoor weathering(Seosan, South Korea) and accelerated weathering(xenon-arc), and the results analysis were evaluated based on yellow-index(YI), scanning electron microscope(SEM/EDS), energy dispersive x-ray spectroscopy(XRD), and gel permeation chromatography(GPC). Among the three materials, processing method development materials1 with UV stabilizer was excellent in weathering. This study can provide basic data for standardization of development and performance evaluation on livestock barn roof.

• Animal Systematics, Evolution and Diversity
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• 제36권4호
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• pp.309-315
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• 2020

The common rough woodlouse Porcellio scaber Latreille, 1804 is newly reported from South Korea with following diagnostic characteristics: the presence of distinct tubercles on body; the strongly developed lateral lobes of head; the presence of notch on tracheal field of pleopod 1 exopod; and distinctly short exopod of uropod. This species is reported to be cosmopolitan, but there were no taxonomic records of it in South Korea. All voucher specimens were collected from humid shaded areas adjacent to the eastern coast of South Korea. Organismal ecology and scanning electron microscope photographs are provided. In addition, the results of CO1 analysis of individuals representing the different color and morphological variations are provided.

• Elastomers and Composites
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• 제57권4호
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• pp.222-230
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• 2022

In this study, a low-heat additive with a crosslink structure was dispersed in asphalt to simultaneously lower the production temperature of, and to modify the asphalt binder. This low-heat additive was prepared by different feeding ratios of styrene-butadiene-styrene (SBS) and polyvinylchloride (PVC) as polymer modifiers, and ZnO as a crosslinking agent. In order to confirm the crosslinking density and compatibility of the crosslink structured low-heat additive with asphalt, surface free energy, swelling ratio, differential scanning calorimetry (DSC), and scanning electron microscope (SEM) parameters were carefully investigated to examine this relationship, and the role of the crosslink structured low-heat additive. In addition, by measuring the penetration and softening point of the asphalt binder, it was confirmed that it corresponds to PG 64-22. With increasing ZnO in the crosslink structured low-heat additive, the swelling ratio decreased, leading to an increase in crosslinking density. The crosslink structured low-heat additive and the asphalt binder were found to be compatible with each other by DSC and SEM analysis.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.219-220
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• 2021

As the area where stone is used in buildings increases, the amount of stone processing increases, and the amount of dust generated in the processing process is increasing, but interest in this is insignificant. In addition, as a result of investigating the dust generated in the dry process, the proportion of SiO2 is about 70%, so there is a concern about the risk of pneumoconiosis caused by breathing. Therefore, it is judged that it is urgent to collect it at the source to prevent damage to workers and environmental pollution.

• Korean Chemical Engineering Research
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• 제59권1호
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• pp.1-5
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• 2021

PEM(Proton Exchange Membrane) 수전해는 PEM 연료전지와 동일한 PEM 전해질 막을 사용하며, 동일한 반응이지만 방향이 반대인 반응에 의해 진행된다. PEM 연료전지는 전해질 막과 촉매의 열화와 내구성에 대해 많은 연구가 진행되어 개발된 열화분석 방법이 많다. 본 연구에서 PEM 수전해 내구성 평가에 PEM 연료전지 내구성 평가 방법 적용이 가능한지 검토하였다. PEM 수전해 열화과정에서 PEM 연료전지와 동일한 조건으로 LSV(Linear sweep voltammetry), CV(Cyclic voltammetry), Impedance, SEM(Scanning Electron Microscope), FT-IR(Fourier Transform Infrared spectroscopy) 등을 분석해 비교하였다. PEM 연료전지처럼 막을 통과한 수소가 Pt/C 전극에서 산화되어 수소투과전류밀도를 측정함으로써 PEM 수전해 고분자 막의 열화정도를 분석할 수 있었다. 수소/질소 유입 조건에서 CV에 의한 전극활성면적(ECSA)을 측정해 전극열화를 분석할 수 있었다. 수소와 공기를 Pt/C 전극과 IrO2 전극에 공급하면서 각 전극의 임피던스를 측정해 전극과 고분자 막의 내구성을 평가할 수 있었다.

• 한국구조물진단유지관리공학회 논문집
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• 제28권3호
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• pp.47-58
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• 2024

본 연구에서는 마이크로 강섬유와 다중벽 탄소나노튜브(multi-walled carbon nanotube, MWCNT)를 혼입한 전도성 모르타르의 발열성능, 휨강도 및 미세구조를 분석하기 위해 실험적으로 수행하였다. 전도성 모르타르 발열성능 및 휨강도 시험에서 MWCNT의 혼입 농도는 시멘트 중량 대비 0.0wt%, 0.5wt% 및 1.0wt%로 선정하였으며, 마이크로 강섬유는 부피 대비 2.0vol%로 혼입하였다. 발열성능 실험은 다양한 인가전압 (DC 10V, 30V, 60V) 및 상이한 전극간격 (40 mm, 120 mm)을 매개변수로 수행하였으며, 양생 재령 28일에서 휨강도를 측정하여 일반 모르타르와 비교, 분석하였다. 더 나아가, 전계방사 주사전자현미경(field emission scanning electron microscope, FE-SEM)을 이용하여 전도성 모르타르의 표면 형상과 미세구조를 분석하였다. 그 결과 MWCNT의 혼입 농도와 인가전압이 증가할수록 발열성능이 향상되었으며, 전극간격이 좁을수록 발열성능이 더욱 향상되는 것으로 나타났다. 하지만 MWCNT의 혼입 농도를 1.0wt%까지 추가하더라도 발열성능은 크게 향상되지 못하였다. 휨강도 시험결과, PM 시편과 MWCNT를 혼입한 시편을 제외한 모든 시편의 평균 휨강도가 4.5 MPa 이상으로 나타나 마이크로 강섬유 혼입에 따른 높은 휨강도를 보였다. FE-SEM 이미지 분석을 통해 시멘트 매트릭스 내 마이크로 강섬유와 MWCNT 입자 사이에 전도성 네트워크가 형성되는 것을 확인하였다.

• 한국전기전자재료학회논문지
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• 제11권6호
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• pp.436-441
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• 1998

$Pt/SrTiO_3/Pb_x(Zr_{0.52}, Ti_{0.48})O_3/SrTiO_3/Si$ structure was prepared by rf-magnetron sputtering method for use in nondestructive read out ferroelectric RAM(NDRO-FEAM). PBx(Zr_{0.52}Ti_{0.48})O_3}$(PZT) and $SrTiO_3$(STO) films were deposited respectively at the temperatures of $300^{\circ}C and 500^{\circ}C$on p-Si(100) substrate. The role of the STO film as a buffer layer between the PZT film and the Si substrate was studied using X-ray diffraction (XRD), Auger electron spectroscopy (ASE), and scanning electron microscope(SEM). Structural analysis on the interfaces was carried out using a cross sectional transmission electron microscope(TEM). For PZT/Si structure, mostly Pb deficient pyrochlore phase was formed due to the serious diffusion of Pb into the Si substrate. On the other hand, for STO/PZT/STO/Si structure, the PZT film had perovskite phase and larger grain size with a little Pb interdiffusion. the interfaces of the PZT and the STO film, of the STO film and the interface layer and $SiO_2$, and of the $SiO_2$ and the Si substate had a good flatness. Across sectional TEM image showed the existence of an amorphous layer and $SiO_2$ with 7nm thickness between the STO film and the Si substrate. The electrical properties of MIFIS structure was characterized by C-V and I-V measurements. By 1MHz C-V characteristics Pt/STO(25nm)/PZT(160nm)/STO(25nm)/Si structure, memory window was about 1.2 V for and applied voltage of 5 V. Memory window increased by increasing the applied voltage and maximum voltage of memory window was 2 V for V applied. Memory window decreased by decreasing PZT film thickness to 110nm. Typical leakage current was abour $10{-8}$ A/cm for an applied voltage of 5 V.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권5호
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• pp.230-235
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• 2004

In this paper, epoxy elasticity factors were investigated by TMA (Thermomechanical Analysis), DMTA (Dynamic Mechanical Thermal Analysis) and FESEM (Field Emission Scanning Electron Microscope) to improve toughness and reduce brittleness of existing epoxy resin. Dumbbell shaped specimens were made and tested at rates of 0, 20 and 35phr (part per hundred resins). TMA temperatures ranged from -2$0^{\circ}C$ to 20$0^{\circ}C$. Tg (glass transition temperature) of elastic epoxy was measured by thermal analysis. Also investigated were thermal expansion coefficient ($\alpha$), modulus and Tan$\delta$ (loss factor). And we analyzed structure through FESEM, could find elastic-factors of elastic epoxy that is not existing-epoxy. In addition, we measured permittivity and Tan$\delta$ for investigation of the electrical properties of elastic epoxy. Permittivity and Tan$\delta$ depend on elastomer composition. Namely, permittivity and Tan$\delta$ increase according to the elastomer contents. For experimental analysis results, 20phr was considered an excellent specimen.

• Journal of Korean Society for Atmospheric Environment
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• 제16권E호
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• pp.29-38
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• 2000

For the detailed characterization of atmospheric aerosol, the analysis of single particle is highly valuable. In this study, to investigate the characteristics of single Asian dust storm particles, scanning electron microscope(SEM) coupled with and energy dispersive X-ray microanalyzer(EDX) and micro-PIXE were applied. Sampling was performed at Kyoto University located in Kyoto, Japan, in spring of 1999. Mass concentration during Asian dust storm events was higher roughly 3∼5 times than measured in the season of the highest concentration. Single particles were generally sharp-edged and irregular in shape and contained mostly crustal elements. Significant amount of S in coarse fraction was detected in individual particles. A large particles in coarse fraction existed as the mixture of soil components and S. A good agreement between the result of SEM-EDX analysis and that iof micro-PIXE analysis was obtained in this study.

• 분석과학
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• 제7권2호
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• pp.155-164
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• 1994

전형적인 Grimm형 방전관을 제작하고 고주파 방전에 의한 금속 및 세라믹시료 분석에 적용하였다. 금속 알루미늄과 알루미나에 대해 방출 스펙트럼을 관찰하였고 방전에 미치는 고주파의 전력과 알곤 기체의 압력에 대한 영향을 관찰하였으며, 시료와 접촉된 전극에 나타나는 DC-bias voltage를 확인하였다. 또한 SEM 사진을 관찰함으로써 rf-sputtering에 의한 알루미나 표면의 미세구조를 확인하였다. 저합금강(BAS 404-405) 중의 망간성분과 황동시료(NIST 1108-1117) 중의 아연성분에 대해 검량곡선을 작성한 결과 양호한 직선성을 보여 주었다.