• 반도체디스플레이기술학회지
• /
• 제11권2호
• /
• pp.75-80
• /
• 2012

Polymer composites which have electrical properties have been studied in various industries. The Multi-walled carbon nanotube (MWCNT) are thought to be reinforcements for polymers because of their high aspect ratio and specially mechanical, thermal and electrical properties. We introduced MWCNT and impact modifier in order to improve thermal and mechanical properties of Polyphenylene sulfide (PPS) and give electric characteristic to PPS. The thermal properties were investigated by Differential scanning calorimeter (DSC) and Thermogravimetric analysis (TGA). The morphology, mechanical properties and electrical characteristic were performed by Field emission scanning electron microscopy (FE-SEM), Izod impact tester and surface resistance meter. As a result, we could find that the PPS/MWCNT composites have high conductivity and good mechanical properties than neat PPS resin.

• 한국연초학회지
• /
• 제29권2호
• /
• pp.80-84
• /
• 2007

This study was conducted to evaluate the prediction of sensory property of smoke from the leaf chemical property and characterize leaf chemical components for the best tobacco taste's leaves in burley tobacco. For analytical and sensory evaluations, sixteen grades were used. The major leaf chemical components to predict the sensory property of smoke were ether extract for tobacco-like, chloride for impact and total nitrogen/nicotine for irritation. Within ${\pm}20\;%$ range of difference, the predictable probabilities of sensory property of smoke from the leaf chemical properties were 100 % for tobacco-like, impact and irritation. As a result of K-means cluster analysis on the basis of tobacco taste, the desirable leaf chemical component contents were $6.5{\sim}6.8\;%$ in ether extract, $0.25{\sim}0.30\;%$ in chloride and $1.26{\sim}1.54$ in total nitrogen/nicotine ratio. This study suggest that the some regression equations may be useful to predict the sensory components of tobacco smoke from a few selected leaf chemical properties in burley tobacco and to select the burley tobacco leaves for enhance the tobacco taste of cigarette.

• 대한기계학회논문집
• /
• 제16권10호
• /
• pp.1869-1876
• /
• 1992

본 연구에서는 고온에서 높은 강도특성을 유지하면서 동시에 내마모성이 뛰어 나 가스터어빈의 부재로서의 사용이 기대되는 탄화규소(SiC) 세라믹에 대하여, 고체입 자의 충격에 의해 생기는 손상에 미치는 입자의 재질 및 크기의 영향을 조사하였다. 또 각 형태의 손상발생 임계치와 강도저하에 미치는 입자크기의 영향에 관해서도 검토 하였다.

• 대한기계학회논문집A
• /
• 제27권3호
• /
• pp.372-380
• /
• 2003

Impact tests were conducted to study the effect of angle ply and metal laminate on impact damage characteristics of Fiber Metal laminates (FML). Impact tests were conducted using drop weight impact machine and damage behavior were analyzed by comparing with load-displacement curve and surface observation and microscopic observation of cross sections. The effect of angle ply on impact characteristics of FML are influenced by property of metal laminate. i.e., when the metal laminate is not enough to strong to prevent fiber debonding, Angle ply FML is superior to singly oriented ply (SOP) FML because angle ply enhance the stiffness by fiber supports and prevent (rack propagation. However, when the metal laminate is enough to strong to prevent fiber debonding, SOP FML is superior to Angle ply FML because the fiber of lower ply in Angle ply FML are more stressed than that of SOP FML.

• 한국세라믹학회지
• /
• 제43권10호
• /
• pp.646-652
• /
• 2006

Several oxynitride glasses were fabricated by means of adding $Si_3N_4$ powders as nitrogen source to Ca-Al-Si-O-N (CAS) and Mg-Al-Si-O-N (MAS) glass powders, and heat-treated in graphite crucible at 1600$^{\circ}C$ for 1 h. The physical and mechanical properties as well as impact resistance were generally increased and compared with each other. The impact resistance properties of those manufactured glasses were evaluated by DOP (depth of penetration) method which is a way to analyze armor materials. There were two means to be used herein; the copper jet impacted at hyper velocity by exploding K2l5 warhead and tungsten heavy alloy (WHA) impact bar at high velocity by firing in 30 mm solid propellent gun. The impact resistance properties against copper jet were increased and then decreased with increasing nitrogen content, while those against WHA bar were not changed apparently with nitrogen content.

• Elastomers and Composites
• /
• 제41권1호
• /
• pp.40-48
• /
• 2006

고무는 금속 및 플라스틱 재료와 달리 작은 하중에서도 큰 변형이 발생되며, 높은 변형 구간에서 탄성특성을 보이는 특징이 있다. 특히 충격흡수 특성이 금속 및 플라스틱보다 우수하므로 제진 및 충격 완충구조물로 널리 활용되고 있다. 충격하중을 받는 고무 구조물의 특성을 평가하기 위하여 자유 낙하형 충격시험기를 이용하여 충격실험을 실시하였으며, ABAQUS/Explicit를 이용하여 유한요소 해석을 수행하였다. 고무의 동강성은 충격펄스의 최대변형량과 충격지속시간으로부터 얻어진 진폭과 주파수를 적용하여 동특성 시험을 수행하고 WLF모델을 적용하여 높은 주파수 대역의 동강성을 예측하였다. 실험을 실시한 $0.3{\sim}l.5J$의 충격에너지 영역에서는 고무의 경도가 증가되면 충격흡수율이 감소되며, 충격에너지가 커질수록 충격흡수율은 감소하는 경향을 나타내었다.

• 대한기계학회논문집A
• /
• 제30권6호
• /
• pp.670-677
• /
• 2006

Vacuum interrupters are used in various switch-gear components such as circuit breakers, distribution switches, contactors. The electrodes of a vacuum interrupter are manufactured of sinter-forged Cu-Cr material for good electrical and mechanical characteristics. Since the closing velocity is 1-2m/s and impact deformation of the electrode depends on the strain-rate at the given velocity, the dynamic material property of the sinter-forged Cu-Cr alloy is important to design the vacuum interrupter reliably and to identify the impact characteristics of a vacuum interrupter accurately. This paper is concerned with the dynamic material properties of sinter-forged Cu-Cr alloy for various strain rates. The amount of chrome is varied from 10 wt% to 30 wt% in order to investigate the influence of the chrome content on the dynamic material property. The high speed tensile test machine is utilized in order to identify the dynamic property of the Cu-Cr alloy at the intermediate strain-rate and the split Hopkinson pressure bar is used at the high strain-rate. Experimental results from both the quasi-static and the high strain-rate up to the 5000/sec are interpolated with respect to the amount of chrome in order to construct the Johnson-Cook and the modified Johnson-Cook model as the constitutive relation that should be applied to numerical simulation of the impact behavior of electrodes.

• Elastomers and Composites
• /
• 제52권1호
• /
• pp.1-8
• /
• 2017

Hydrolysis resistance and mechanical property changes of polyketone (POK)/glass fiber (GF) composites were investigated for GF concentrations varying between 30 and 50%. The hydrolysis resistance of GF filled POK and polyamide66 (PA66, hydrolysis resistant grade) composites were compared. As shown by the experimental results, increasing the immersion time of the composites in a monoethylene glycol (MEG)/water solution at $120^{\circ}C$ had no impact or resulted in slightly decreased mechanical properties such as the tensile strength, tensile modulus, and strain at break in case of POK composites, whereas the mechanical properties of PA66 composites showed a significant drop. Increasing GF concentrations increased the tensile strength, tensile modulus, flexural strength, and flexural modulus of POK composites; however, impact strength did not show significant changes. Hydrolysis mechanisms of POK and PA66 are discussed.

• 대한금속재료학회지
• /
• 제47권3호
• /
• pp.195-201
• /
• 2009

This paper is concerned with effects of Mn and heat-input on the mechanical properties of EGW welds. Four different kinds of welding consumables were fabricated by varying Mn contents such as 1.3, 1.5, 1.7, 2.0%Mn and each consumable was welded for EGW on four heat-input conditions between 190 and 340 KJ/Cm. Mn contents were decreased as heat-input increases and alloy elements (C, Si, Ti, B, Al) to deoxidize easily also revealed similar tendency to Mn. Their microstructure, Charpy impact property and strength were investigated, and it is found that Charpy impact property and strength exhibit a strong dependence on change of microstructure by Mn contents and heat-input. The increase of Mn contents or the decrease of heat-input made the microstructure fine and increase volume fraction of acicular ferrite, thereby leading to the great improvement of Charpy impact property and strength. In case of single EGW, optimum Mn contents are over 1.7% for the toughness and strength.

• 한국연초학회지
• /
• 제29권2호
• /
• pp.74-79
• /
• 2007

This study was conducted to evaluate the prediction of sensory property of smoke from leaf chemical property and characterize leaf chemical components for the best tobacco taste's leaves in flue-cured tobacco. For analytical and sensory evaluations, one hundred and forty grades were used. The major leaf chemical components to predict the sensory property of smoke were nicotine for impact, irritation and off taste & odor, and total sugar/nicotine ratio for tobacco taste. Within ${\pm}20%$ range of difference, the predictable probabilities of sensory property of smoke form leaf chemical property were 80.0% for off taste & odor and $91.4{\sim}96.4%$ for impact, irritation and tobacco taste. As a result of K-means cluster analysis on the basis of tobacco taste, the desirable leaf chemical component contents were $2.77{\sim}3.55%$ in nicotine and $5.1{\sim}6.9$ in total sugar/nicotine ratio. This study suggest that the some regression equations may be useful to predict the sensory property of tobacco smoke from a few selected leaf chemical components in flue-cured tobacco and to select the flue-cured tobacco leaves for enhance the tobacco taste of cigarette.