• 한국전기전자재료학회논문지
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• 제24권7호
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• pp.568-573
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• 2011

AZO (Al doped ZnO) thin films were deposited on the quartz substrates with thickness variation from 25 to 300 nm by using PLD (pulsed laser deposition). XRD (x-ray diffractometer), SPM (scanning probe microscopy), Hall effect measurement and uv-visible spectrophotometer were employed to investigate the structural, morphological, electrical and optical properties of the thin films. XRD results demonstrated that films were preferrentially oriented along the c-axis and crystallinity of film was improved with increase of film thickness. As for the surface morphologies, the mean diameter and root mean square of grains were increased as the film thickness was increased. When the film thickness was 200 nm, the lowest resistivity of $4.25{\times}10^{-4}\;{\Omega}cm$ obtained with carrier concentration of $6.84{\times}10^{20}\;cm^{-3}$ and mobility of $21.4\;cm^2/V{\cdot}S$. All samples showed more than 80% of transmittance in the visible range. Upon these results, it is found that the samples thickness can affect their structural, morphological, optical and electrical properties. This study suggests that the resistivity can be improved by controlling film thickness.

• Macromolecular Research
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• 제17권11호
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• pp.856-862
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• 2009

This study examined the effects of liquid and solid additives on the morphological, mechanical and thermal insulating properties of rigid polyurethane foams (PUFs). The PUFs synthesized with tetramethylsilane (TEMS) as a liquid-type additive showed a smaller average cell size and lower thermal conductivity than those with the aerosil 200 and clay 30B as solid-type additives. When TEMS was added, the average cell size of the PUF became more uniform and finer due to the reduced surface tension of the polymer solution, which increased the nucleation rate and number of bubbles produced and reduced cell size. The PUFs with TEMS showed the highest closed cell contents among the PUFs prepared using TEMS, aerosil 200 and clay 30B. This suggests that the insulation properties of PUF can be determined by both the size of the cell structure and the amount of closed cell contents in the system. The compression and flexural strengths of the PUF increased slightly when the aerosil 200, clay 30B and TEMS were added compared those of the neat PUF. The reaction profiles of the PUFs showed a similar gel and tack tree time with the reaction time among the PUFs synthesized with three different additives and neat PUF. This suggests that the nucleating additives used in this study do not affect the bubble growth of the chemical reaction, and the additives may act as nucleating agents during the formation of PUF. From the above results of the cell size, thermal conductivity, closed cell contents and reaction profile of the PUFs, liquid-type nucleating agent, such as TEMS, is more effective in decreasing the thermal conductivity of the PUF than solid-type nucleating agent, such as aerosil 200 and clay 30B.

• 현장농수산연구지
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• 제22권2호
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• pp.81-88
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• 2020

국내에서 육성된 산느타리버섯 8품종을 병재배 방식으로 재배특성을 조사하였다. 8품종의 자실체 형태는 전체적으로 갓직경이 크고 대는 짧은 형태였다. 대는 편심생으로 갓에 결합되어 있다, 자실체의 길이가 가장 긴 품종은 여름2호(72.8mm)이고 가장 짧은 품종은 여름1호(33.8mm)이다. 대의 두께는 여름2호, 호산의 순서로 두겁고 15.5mm, 12.8mm 였다. 갓의 직경은 45.8-62,3mm로 약산이 가장 작고 여름2호가 가장 큰 갓을 지닌 것으로 나타났다. 전체 무게(수확량)은 여름2호가 80.7g으로 가장 많은 생산량을 보였고 여름1호가 35.5g으로 가장 낮은 수치를 보였다. 가장 갓색이 밝은 품종은 여름2호로 55.6이었고 호산도 54.1이었다. 특징적으로 갓색이 가운데 부분은 엷은 편이었으며 가장자리가 더 진하게 착색되었다. 평균적 발이소요일과 생육소요일은 각각 4.6일과 8.0일이어서 발이 후 3.4일 만에 수확을 완료하였다.

• 열처리공학회지
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• 제24권2호
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• pp.82-86
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• 2011

The influences of Bi addition on morphological modification of $Mg_2Si$ phase and mechanical properties were investigated in Mg-7%Al-0.5%Si casting alloy. It was found that the addition of 0.3%Bi changed the $Mg_2Si$ morphology from coarse Chinese script type to polygonal type, and significantly decreased the size to ~5 ${\mu}m$ or less with the increase of number density. The modification of $Mg_2Si$ phase by the addition of Bi resulted in the improvement of tensile properties of the Mg-Al-Si alloy at RT and $175^{\circ}C$.

• 천문학회보
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• 제40권1호
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• pp.76.3-77
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• 2015

MIR colors are an excellent tool to investigate the transition phase of galaxy evolution in terms of star formation at various phases. The Coma supercluster is the nearest massive supercluster, hosting two main clusters, the Coma (Abell 1656) and Leo (Abell 1367) clusters, and one galaxy group, the NGC 4555 group, providing an ideal laboratory to study how galaxies evolve depending on environment. We present the results of a study for MIR properties of galaxies in the Coma supercluster using multi-wavelength data from the optical to MIR including the Sloan Digital Sky Survey Data Release 12 and the Wide-field Infrared Survey Explorer. We investigate differences in MIR properties of galaxies among three galaxy systems, and discuss the results in relation with star formation history and morphological transformation of galaxies.

• Bulletin of the Korean Chemical Society
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• 제30권9호
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• pp.2071-2076
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• 2009

The single-walled carbon nanotubes (SWCNTs) produced by chemical vapor deposition (CVD) were directly fluorinated with fluorine ($F_2$) gas in a temperature range 20 ~ 400 ${^{\circ}C}$. The surface properties and morphology of the SWCNTs were investigated in terms of fluorination temperature. As a result, Raman spectra showed a pair of bands at 1340 and 1590 $cm^{-1}$ peculiar to disordered $sp^2$-carbons. These results indicated that C-F bonds were formed on the rear surfaces of the nanotubes by fluorination, while the external surfaces as well as the layers between the internal and external surfaces retained their $sp^2$-hybridization. XPS analysis exhibited that fluorine atoms were bonded to carbon atoms on internal surfaces (rear surfaces) of the nanotubes and the amount of fluorine attached on the nanotubes was increased with increasing the fluorination temperature. Consequently, the direct fluorination of carbon nanotubes led to functionalization and modification of pristine nanotubes with respect to surface and morphological properties.

• 대한기계학회논문집A
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• 제30권7호
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• pp.794-799
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• 2006

In recent years, the use of natural fiber as reinforcement in polymer composites to replace synthetic fiber such as glass fiber is receiving increasing attention. Because of increasing usage according to the high demand, the cost of thermoplastic has increased rapidly over the past decades. We used a thermoplastic polymer(polypropylene) as the matrix and a lignocellulosic material(rice-husk flour) as the reinforcement filler to prepare a particle-reinforced composite to examine the possibility of using lignocellulosic material as reinforcement filler and to determine data of test results for physical, mechanical and morphological properties of the composite according to the reinforcement filler content in respect to thermoplastic polymer, In this study, PLA/PP rice-husk fiber-reinforced thermoplastic composites that made by the hot press molding method according to appropriate manufacturing process was evaluated as mechanical properties.

• Applied Microscopy
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• 제47권1호
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• pp.19-28
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• 2017

Since graphene was discovered in 2004, two-dimensional (2D) materials have been actively studied. Especially, 2D transition metal dichalcogenides (TMDs), such as $MoS_2$ and $WS_2$, have been the subject of significant research because of their exceptional optical, electrical, magnetic, catalytic, and morphological properties. Therefore, these materials are expected to be used in a variety of applications. Furthermore, tuning the properties of TMDs is essential to improve their performance and expand their applications. This review classifies the various doping methods of 2D TMDs, and it summarizes how the dopants interact with the materials and how the performance of the materials improves depending on the synthesis methods and the species of the dopants.

• 한국의류산업학회지
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• 제13권2호
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• pp.279-284
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• 2011

In this study, the process of preparation nonwoven with coated carbon nano fibers (CNFs) /poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite solution is described. The various contents of CNFs/PVDF-HFP composite coated nonwoven were prepared and characterized by morphological, mechanical, and electrical methods. Nonwovens are coated with CNFs/PVDF-HFP composite solution and decreased the pick up ratio with increasing CNFs contents in range from 0% to 16%. In the results of SEM images, it was clear that the CNFs were evenly distributed in coated nonwoven by SEM images, the existence of CNFs in coated nonwoven was confirmed regularly. The mechanical properties of various contents of CNFs/PVDF-HFP coated nonwoven were examined. The tensile linearity and compression linearity increased with increasing CNFs contents. The electrical properties of the CNFs/PVDF-HFP coated nonwoven increased with increasing CNFs contents.

• Korea-Australia Rheology Journal
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• 제16권3호
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• pp.147-152
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• 2004

Ultrasound-assisted melt mixing was applied to blending polystyrene (PS) and low density polyethylene(LDPE). The influence of the ultrasonic irradiation on the morphology and mechanical properties of the blends was investigated. It was observed that the domain sizes of the blend were significantly reduced and phase stability was well sustained even after a thermal treatment. Such morphological feature was consistent with the improvements in mechanical performance of the blends. The desirable results of ultrasonic compatibilization are mainly attributed to the in-situ formation of PS-LDPE copolymers as confirmed by a proper separation experiment. An important relationship between ultrasonic irradiation time and mechanical properties is revealed and an issue on the thermal stability of the blend is discussed.