• 한국표면공학회지
• /
• 제24권2호
• /
• pp.73-79
• /
• 1991

Recent studies son surface coatings have shown that the change of physical, chemical and crystallographic structure analysed and observed according to the deposition process variables has the effects on the resultant film properties. Under the same preparation condition conditions of the substrate and process variables, physical morphology variations characterized by substrate temperature and bias which offect the surface mobility of adatom and adhesion variations related to the formation of Ti interlayer were considered in the present study. Microhardness showed the highest value around 40$0^{\circ}C$ of the substrate temperature and increased with the substrate bias. Adhesion was improved with the increase of substrate temperature and bias. An interlayer of pure titanium formed prior to deposition of TiN improves the adhesion at its optimum thickness. These results were explained by the change of physical morphology and phase analysis.

• Journal of Welding and Joining
• /
• 제32권5호
• /
• pp.80-86
• /
• 2014

We have successfully fabricated high strengthening Cu/STS/Cu 3 layered clad metal of $70kgf/mm^2$ grade for electric device lead frame, and investigated thermal effect of the mechanical and physical properties on the Cu/STS/Cu 3 layered clad metal lead frame material at different temperatures ranging from RT to $200^{\circ}C$. The fabricated clad metal shows a good thermal stability under 6% degrading of mechanical tensile strength and hardness change at $200^{\circ}C$ and also physical properties show stable thermal and electrical conductance of over $220W/m{\cdot}K$ and 58.44% IACS upto the $200^{\circ}$. The results confirm that fabricated high strengthening Cu/STS/Cu 3 layered clad metal can be applied for the high performed electrical lead frame devices.

• Korean Chemical Engineering Research
• /
• 제48권1호
• /
• pp.93-97
• /
• 2010

본 연구에서는 수정된 T-history 법을 사용하여 백신 또는 의약품들의 수송 시 냉매로 사용될 수 있는 $0{\sim}15^{\circ}C$의 상전이 온도를 갖는 유기 상전이 소재들과 이중 두 물질의 혼합물들의 열용량, 잠열, 비열과 같은 열 물성을 측정하였다. 순수한 파라핀들을 측정한 결과, 각 물질들의 상전이 온도를 고려하여 최적의 냉각 속도를 유지하며 측정을 하는 것이 열물성의 신뢰성을 향상시킬 수 있음을 알 수 있었고, 특히 혼합물의 열 물성 측정에 적용할 경우, 수정된 T-history 법의 사용은 기존의 DSC 분석에 사용하는 시료의 양이 소량이므로 유발될 수 있는 결과의 부정확성 등의 문제점을 해결하는데 기여할 수 있음을 알 수 있었다.

• Journal of the Korean Wood Science and Technology
• /
• 제44권5호
• /
• pp.767-775
• /
• 2016

목재의 재질특성은 토양, 지형, 강우, 기후변화 등의 환경적 인자뿐만 아니라 임분 특성에 의해서도 바뀌게 된다. 지역 성림기원에 따라 종가시나무 목재의 물리 역학적 특성을 비교 검토하였다. 지역에 따른 비교분석은 전라남도와 제주도의 종가시나무 천연림을 대상으로 실시하였다. 지역에 따른 결과에서 제주지역은 전남지역에 비하여 높은 생장률을 나타내었으며 역학적 특성에서는 휨강도를 제외한 여러 역학적 특성에서 상관관계가 인정되었으나 실제 값으로 볼 때 큰 차이는 나타나지 않았다. 또한 성림기원에 따른 결과에서는 생장률 및 역학적 특성에서 특별한 차이가 나타나지 않았다.

• Elastomers and Composites
• /
• 제46권2호
• /
• pp.158-163
• /
• 2011

해수 하에서 경시 변화에 따른 경질 폴리우레탄 폼(PUF)의 물성 변화를 알아보기 위해 방향족 폴리에스테르 폴리올, 지방족 폴리에스테르 폴리올과 지방족 폴리에테르 폴리올 함량에 따라 경질 폴리우레탄 폼을 합성하였다. 해수 하에서 PUF의 물성변화를 고찰하기 위해 만능시험기, 시차 주사 열량계, 경도 측정기, 적외선 분광계를 이용하였다. 방향족 폴리에스테르 폴리올의 함량이 증가함에 따라 해수 하에서 경시 변화에 따라 PUF의 압축강도와 경도의 감소폭은 증가하였다. 해수 하에서 PUF의 유리전이온도는 증가하였는데 적외선 스펙트럼 분석 결과 우레탄과 우레아의 피크는 감소하고, 알로파네이트와 바이우렛의 피크는 증가한 것을 알 수 있었다. 해수 하에서 PUF는 가교도가 증가하여 폼이 brittle하게 형성됨에 따라 유리전이온도가 증가하였지만 가수 분해로 인하여 기계적 물성이 저하된 것으로 사료 된다.

• 한국염색가공학회지
• /
• 제31권4호
• /
• pp.288-297
• /
• 2019

The specimens were heat treated at 180℃, 190℃, 200℃, 210℃ and 220℃ to observe the change of the physical properties of the double raschel pile fabric. The density, tensile strength, weight, elongation, dyeing characteristics, fabric surface morphology and cross sectional shape were observed by heat treatment temperature. Compared with untreated samples, weight, density and tensile strength were increased with increasing heat treatment temperature. No increase was observed at 220℃. In the case of elongation, it increased to 190℃ but thereafter it could not be observed. In the case of uprightness of brushed hair, it was observed that the gap between the yarns was narrowed and the density was increased and the straightness of the yarn and pile yarn was improved by widening the heat treatment temperature. As a result, it was observed that the uprightness was remarkably improved and the bulky properties was increased. It was also observed that the increase of the dyeability was observed with increasing the heat treatment temperature.

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2003년도 가을 학술논문집
• /
• pp.517-523
• /
• 2003

방사선장 하에서의 탈기막 재질의 물성에 미치는 방사선의 영향에 관한 연구를 수행하였다. PP에 미치는 방사선속을 계산하기 위해 MCNP4A Code를 이용하였으며 MCNP4A Code를 이용한 광자선속을 계산하기 위하여 탈기장치와 PP 막을 봉 구조로 규격화하였다. 양단차폐 계통에 사용되는 탈기막 재질인 PP의 변형은 계통수의 방사능이 매우 낮기 때문에 거의 없을 것으로 평가되었으며 작업자의 피폭도 무시할 정도인 것으로 판단되었다. 검토결과, 원자력발전소의 원자로 계통수 처리를 위해 방사선장하에서 노출되는 폴리프로필렌 탈기막의 재질은 건전성이 그대로 유지될 수 있음을 평가하였다.

• Elastomers and Composites
• /
• 제30권3호
• /
• pp.218-228
• /
• 1995

To make filler loaded conducting rubber which has excellent electronical and physical properties, CR and NBR were mixed with barium ferrite(BaO.6Fe2O3). From the result of this study, vulcanization characteristics shows that curve is upgraded as the filler concentration increases and CR has higher torque than NBR. In physical properties, elongation being higher, modulus comes to decrease. Tear strength gradually decrease after showing the maximum point when is in the 100phr in CR. Resilience is not good to cause the increase in filler concentration. In electrical properties, conductivity becomes low when filler concentration increase. The increase of voltage makes a conductivity grown, but the rate change is weak. The influence of temperature hardly changes on increasing temperature. The morphology and the dispersion of a conductivity filler in vulcanizates through SEM were good. The more filler concentration increases, the shorter the particle interval is.

• Elastomers and Composites
• /
• 제50권1호
• /
• pp.35-48
• /
• 2015

Polyhedral oligomeric silsesquioxane (POSS) is an important inorganic-organic hybrid material with a three-dimensional structure. Polyurethane (PU) is a widely applied polymer that has versatile properties with the change of two phase structure. When POSS is incorporated into PU by physical or chemical methods, many properties can be greatly improved, such as mechanical properties, thermal stability, biodegradation resistance, and water resistance. This paper reviews the recent progress in preparation, structure, and performance of POSS-modified polyurethane from the viewpoint of physical blending and chemical modification.

• 대한기계학회논문집A
• /
• 제22권4호
• /
• pp.801-810
• /
• 1998

Modeling and analysis of dynamic systems generally demand their resutls to be interpreted each other with a physical sense. It sometimes requires that there should exist a unified tool in the treatment of dynamic systems which can be applied to both their modeling and analysis equally. This paper shows how models just after the progress of modeling via bond graph standards are converted to ones which are appropriate for analyzing a dynamic system in the frequency domain. Four bond graph prototypes are introduced to obtain frequency properties of dynamic systems such as zero stability, relative order, zero and pole dynamics, etc. directly from bond graphs, and the method are proposed which reduces nearly all models of bond graph standards to one of the prototypes without any change of physical similarity. This procedure as a tool for the structural reduction of bond graphs and finding frequency properties of a dynamic system is further investigated to survey its effectiveness through an example.