• 한국염색가공학회지
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• 제21권3호
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• pp.26-36
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• 2009

The objective of this study is to investigate the elution characteristics of the partial dispositioned hollow nylon filament and the mechanical properties of the eluted fabrics according to the weight reduction conditions. For this purpose, the partial dispositioned nylon/PET composite filament, SDY 70d/48f was prepared, and warp beam was also prepared on the sizing machine using these yarns. Four kinds of woven fabrics were designed with different warp and weft densities and these fabrics specimens were eluted with weight reduction conditions of two kinds of NaOH concentration (30, 40g/l), three kinds of weight reduction temperature (50, 60, $85^{\circ}C$) and two kinds of weight reduction time (30, 60min). The eluting rates of these fabrics specimens were analysed with various weight reduction conditions. The eluting characteristics of these fabrics were discussed with the cross-section of nylon hollow filament measures by SEM. Finally, the mechanical properties of the partial dispositioned hollow nylon fabrics were measured and discussed with various weight reduction conditions.

• Nuclear Engineering and Technology
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• 제41권1호
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• pp.11-20
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• 2009

Radiation effects on materials are inherently multiscale phenomena in view of the fact that various processes spanning a broad range of time and length scales are involved. A multiscale modeling approach to embrittlement of pressure vessel steels is presented here. The approach includes an investigation of the mechanisms of defect accumulation, microstructure evolution and the corresponding effects on mechanical properties. An understanding of these phenomena is required to predict the behavior of structural materials under irradiation. We used molecular dynamics (MD) simulations at an atomic scale to study the evolution of high-energy displacement cascade reactions. The MD simulations yield quantitative information on primary damage. Using a database of displacement cascades generated by the MD simulations, we can estimate the accumulation of defects over diffusional length and time scales by applying kinetic Monte Carlo simulations. The evolution of the local microstructure under irradiation is responsible for changes in the physical and mechanical properties of materials. Mechanical property changes in irradiated materials are modeled by dislocation dynamics simulations, which simulate a collective motion of dislocations that interact with the defects. In this paper, we present a multi scale modeling methodology that describes reactor pressure vessel embrittlement in a light water reactor environment.

• Advances in nano research
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• 제14권1호
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• pp.81-92
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• 2023

In this work, the effect of the addition of Aerosil 200, an insulating resin applied in many industries, on the water absorption of cement plast mixture has been experimentally evaluated. First, the preparation stages of cement plast mixture was evaluated based on corresponding standards and then, the effect of the addition of Aerosil 200 nanoparticles (NPs) to cement plast mixtures with sand weight percentage range of 0-0.1% on the variation of water absorption properties was evaluated based on National Standard Institution of Iran 20185 for Concrete Flooring Blocks - Requirements and Test Procedures. Based on the obtained results, it could be found that excessive addition of NPs did not affect the physical properties of the final product. Water absorption percentage was increased in the weight percentage of cement. By the increase of the amount of Aerosil 200 NPs in the prepared cement plast mixture, the percentage of water absorption in weight percentage of sand was decreased. Cement plast with NPs presented significantly lower water absorption than that without NPs.

• 한국지반신소재학회논문집
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• 제16권4호
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• pp.221-230
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• 2017

선행 연구에서 PVP를 이용하여 수용성 폴리머 파우치를 개발하였다. 그러나 개발된 재료의 용융점이 매우 낮아 재료의 성형 시 문제점이 많아 대량생산 시 필요한 성형, 제작이 불가능하였기에 성형성이 우수한 새로운 재료 조합을 이용하여 폴리머 파우치를 개발하였다. 새롭게 선정된 PEG의 수용성 변화 및 지반공동 내 보강 시 파우치의 기계적 물성을 만족해야한다. 따라서 PEG와 LLDPE, TALC 블렌딩 비율에 따른 특성평가를 실시하였는데 각 원료의 비율에 따라 발생하는 성질이 다르기 때문에 실험을 통해 적정 비율을 찾는 것이 중요하기 때문이다. 이러한 블렌딩을 통해 수용성 특성은 유지하며 인장 및 충격강도가 증진된 폴리머 파우치를 개발하였다. 최종 개발된 제품을 이용하여 직접전단 실험을 실시한 결과, 폴리머 파우치의 지반강도 효과를 확인할 수 있었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1998년도 춘계학술대회 및 발표대회 강연 및 발표논문 초록집
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• pp.6-6
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• 1998

In 1957, the first magnetic disk drive compatible with a movable head was introduced as an external file memory device for computer system. Since then, magnetic disks have been improved by increasing the recording density, which has brought about the development of a high performance thin film magnetic head. The thin film magnetic head has a magnetic circuit on a ceramic substrate using IC technology. The physical property of the substrate material is very important because it influences the tribology of head/disk interface and also manufacturing process of the head. $Al_{2}O_{3}$-TiC ceramics, so called ALTIC, is known to be one of the best substrate materials which satisfies this property requirement. Even though the head is not in direct contact with the disk, frequent instantaneous contacts are unavoidable due to its high rotating speed and the close gap between them. This may cause damage in the magnetic recording media and, thus, it is very important that the magnetic head has a good wear resistance. $Al_{2}O_{3}$-TiC ceramics has an excellent tribological property in head/disk interface. Manufacturing process of thin film head is similar to that of IC, which requires extremely smooth and flat surface of the substrate. The substrate must be readily sliced into the heads without chipping. $Al_{2}O_{3}$-TiC ceramics has excellent machineability and mechanical properties. $Al_{2}O_{3}$-TiC ceramics was first developed at Nippon Tungsten Co. as cutting tool materials in 1968, which was further developed to be used as the substrate materials for thin film head in collaboration with Sumitomo Special Metals Co., Ltd. in 1981. Today, we supply more than 60% of the substrates for thin film head market in the world. In this paper, we would like to present the sintering process of $Al_{2}O_{3}$-TiC ceramics and its property in detail.

• 한국재료학회지
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• 제22권5호
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• pp.227-236
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• 2012

Ionomer is a thermoplastic that is composed of covalent bonds and ionic bonds. It is possible to use this material in processes such as injection molding or extrusion molding due to the material's high oil resistance, weatherproof characteristics, and shock resistance. In this study, a new ionomer having a multifunctional group was prepared by a stepwise neutralization system with the addition of acidic and salt additives. In step I, to increase the contents of the multifunctional group and the acid degree in ethylene acrylic acid (EAA), MGA was added to the ionomer resin (EAA). A new ionomer was prepared via the traditional preparation method of the ionic cross-linking process. In step II, metal salt was added to the mixture of EAA and MGA. The extrusion process was performed using a twin extruder (L/D = 40, size : ${\varphi}30$). Ionomer film was prepared for evaluation of gas permeability by using the compression molding process. The degree of neutralized and ionic cross-linked new ionomer was confirmed by FT-IR and XRD analysis. In order to estimate the neutralization of the new ionomer film, various properties such as gas permeation and mechanical properties were measured. The physical strength and anti-scratch property of the new ionomer were improved with increase of the neutralization degree. The gas barrier property of the new ionomer was improved through the introduction of an ionic site. Also, the ionic degree of cross-linking and gas barrier property of the ionomer membrane prepared by stepwise neutralization were increased.

• Composites Research
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• 제17권1호
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• pp.10-17
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• 2004

본 연구에서는 이관능성 에폭시(DGEBA)와 polymethylmethacrylate(PMMA)를 블랜딩하여 열적 특성과 기계적 계면특성을 측정하였다. 열적 특성은 DSC, DMA, 그리고 TGA를 이용하였으며, 블랜드의 기계적 계면특성을 측정하기 위해 contact angle로 표면자유에너지를 조사하였고, 파괴인성은 $K_{IC}$로 측정하고 $K_{IC}$ 실험 후 파괴단면을 SEM을 이용하여 관찰하였다. 실험 결과, 경화 온도와 유리전이 온도는 PMMA의 첨가에 의해 증가하는 것을 확인할 수 있었다. 또한 블랜드의 표면자유에너지는 PMMA의 저함량에서 높은 값을 나타내었고, 이는 비극성 요소의 증가와 극성 요소의 존재에 의한 것으로 판단된다. 블랜드의 파괴인성 측정 결과 5 phr에서 최대값을 나타내었다. 이는 DGEBA/PMMA 간의 상용성 또는 거대분자 사슬에서 물리적 결합의 증가에 기인하는 것으로 판단된다.

• Elastomers and Composites
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• 제43권3호
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• pp.173-182
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• 2008

고무나 우레탄과 같은 고 탄성력을 이용하여 튜브를 임의의 형상으로 성형하는 고 탄성체 성형방법은 타 공정에 비해 높은 치수 정밀도와 생산 공정의 단축, 에너지 절감 등을 기대할 수 있는 차세대 성형기술이라 할 수 있다. 본 연구에서는 탄성체에 대한 소재 물성시험과 특성평가를 통해 고 탄성체 성형에 적합한 소재를 선정하고 시험으로 얻어진 응력-변형률을 이용하여 비선형 재료상수를 결정하여 성형해석에 필요한 물성 데이터를 확보하였다. 또한, 랙튜브에 대한 유한요소해석을 통해 탄성체의 두께변화에 따른 공정변수의 영향을 검토하였다.

• Journal of the Korean Wood Science and Technology
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• 제43권6호
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• pp.721-729
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• 2015

목재의 재질특성은 토양, 기후, 임분특성 등의 환경적 요인뿐만 아니라 인위적인 처리에 의해서도 바뀌게 되므로 남부지역의 전라남도 완도 수목원에서 무간벌, 약도간벌, 강도간벌의 간벌강도에 따른 목재의 조직 물리 역학적 특성을 평가 분석한 결과 간벌 강도에 따라 여러 조건에서 높은 상관관계를 나타내었다. 특히 간벌강도는 연륜폭과 역학적 특성에서 밀접한 상관관계를 나타내었다. 본 연구결과 붉가시나무의 간벌강도와 재질특성 사이에서 상관관계가 나타났고 이러한 결과는 목재를 시업체계와 육림방법 시스템에 적용할 수 있는 기초자료로서 활용가치가 높을 것으로 판단된다.

• 패션비즈니스
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• 제11권5호
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• pp.51-63
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• 2007

Chitosan, a natural cationic macromolecular material, has been known for its moisturizing and healing effect due to the coating action based on strong ionic bonding when the chitosan is treated on hair strands. In this study, the acidic aqueous chitosan solution was prepared to treat healthy hair, and damaged hair due to bleaching, relatively thin hair and thick hair specimens. The chitosan treatment effect was reviewed by comparing spectrophotometric and mechanical characteristics of the chitosan treated and untreated specimens. Electrostatic voltage was somewhat reduced after the chitosan treatment. Smoothly coated surface was observed, in the SEM images, especially for damaged hair specimens. The values of breaking strength, which is one of the indicators of the internal characteristics of hair, was high in the case of chitosan treated samples. The values of elongation was also high in the case of chitosan treated samples, which proves the chitosan treatment effect. The friction force, one of the indicators of surface characteristics, was reduced for the case of chitosan treated samples.