• Elastomers and Composites
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• 제49권3호
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• pp.191-198
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• 2014

산성기를 도입한 폴리우레탄에 나노산화아연을 첨가하여 열가소성 폴리우레탄 탄성체를 합성하였으며, 합성된 폴리우레탄 탄성체의 기계적물성, 열적특성, 접촉각, 그립특성을 평가하였다. 그리고 산화아연의 함량과 입자 크기가 폴리우레탄 탄성체에 미치는 영향에 대해서 연구하였다. 나노산화아연을 도입한 경우 이온결합이 형성되어 산성기에 의한 수소결합과 동시에 작용하기 때문에 인장강도, 마모 등 기계적 물성 및 그립특성이 향상되는 것이 확인되었다. 폴리우레탄내의 산화아연 함량에 따른 물성평가 결과 나노산화아연 함량이 증가할수록 이온결합 도입에 의한 친수성이 커져서 wet slip이 지속적으로 상승되었으며, 기계적 물성은 산화아연에 의한 이온화율 50%까지 향상되다가 그 이후에는 감소되는 현상을 나타내었다.

• Elastomers and Composites
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• 제46권4호
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• pp.329-334
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• 2011

일반적으로 butyl 고무(IIR : isobutylene isoprene rubber)는 우수한 내기체투과성 및 저반발 탄성체로서 우수한 충격흡수성을 갖는다. 본 실험에서는 butyl고무에 EPDM(ethylene propylene diene monomer)을 기계적 혼련법으로 blend 혼련물을 제조하여 이들의 가교 거동, 물리적 성질 및 내오존성 등을 측정하였다. EPDM 고무량이 증가할수록 최적 가황시간이 단축되는 경향을 보였다. 기체투과속도 테스트에 의한 내기체투과성 측정 결과 butyl고무량이 50 wt% 이상일 경우에는 기체투과도가 현저히 감소하였다. 한편 butyl rubber/EPDM 블렌드의 경우에 EPDM의 함량이 25 wt.% 이상 함유될 경우 내오존성이 향상되어 50 pphm, $50^{\circ}C$, 120시간 조건에서도 아무런 표면변화가 없었다.

• 한국기계가공학회지
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• 제21권5호
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• pp.28-33
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• 2022

A pipe is a hollow, long-form part that is primarily used to transport fluids, such as liquids or gases. Pipes are used in a range of applications in different fields from mechanical purposes to architecture and electrical uses. Despite the significance owing to various usability of pipes, few studies have been conducted using the physical property test method. The tensile test is widely used as a method to check the physical properties of the pipe. The existing pipe tension test contains the possibility to cause errors, which are fractures outside the gauge distance and cross-sectional deformation of the pipe. In this study, a novel pipe tension test method using a jig is presented and pipes with various materials are tested. It is expected that the proposed method can reduce errors that occur in conventional pipes and also obtain more accurate values to enable more efficient testing.

• 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.

• 한국정밀공학회지
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• 제29권5호
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• pp.584-590
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• 2012

The structural and functional disorder of a detrusor induces a bladder hypertrophy and degenerates a bladder muscle gradually by preventing normal urination. Thus, the thickness of the bladder wall has been increased in proportion to the degree of bladder outlet obstruction. In this study, the mechanical characteristics of the detrusor is analyzed for the physical properties and the thickness changes of the bladder muscle using a mathematically analytic method. In order to obtain the mechanical property of the bladder muscle, the tensile test of porcine bladder tissue is performed because its property is similar to that of human. The result of tensile test is applied to the mathematically model as Mooney Rivlin coefficients which represent the hyperelastic material. The model of the bladder is defined as the spherical shape with the initial volume of 50ml. The principal stress and strain according to the thickness are analyzed. Also, computer simulations for three types of the material property for the model of the bladder are performed based on the fact that the stiffness of the bladder is weakened as the progress of the benign prostatic hyperplasia. As a result, the principal stress is 341kPa at the initial thickness of 2.2mm, and is 249kPa at 6.5mm. As the bladder wall thickness increases, the principal stress decreases. The principal stress and strain decrease as the stiffness of the bladder decreases under the same thinkness.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1461-1471
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• 2002

Linear motor has a lot of advantages in comparison with conventional feed mechanisms: high velocity, high acceleration, good positioning accuracy and a long lifetime. An important disadvantage of linear motor is its high power loss and heating up of motor and neighboring machine components in operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. In this paper Finite-Element-Method for the thermal behavior of synchronous linear motor is introduced, which is useful for the design and manufacturing of linear motors. By modeling the linear motor the orthotropic physical properties of the sheet metal and windings were considered and convective coefficient in the water cooler and to the surroundings was defined by analytical and experimental method. The calculated isothermal lines could analyze the heat flow in the linear motor.

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

• Journal of the Korean Wood Science and Technology
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• 제52권1호
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• pp.87-100
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• 2024

Wood has different properties depending on the species or growth area. Therefore, in order to use wood efficiently, it is necessary to have a proper understanding of the characteristics of wood depending on the species and the appropriate use for them. In particular, in order to effectively use more than 1,000 species of woody plants in South Korea as wood, it is necessary to evaluate the characteristics of various Korean domestic woods and make a database of them. In this study, the anatomical properties (length and width of tracheid, cell wall thickness), physical properties (specific gravity and shrinkage), mechanical properties (bending strength, compressive strength, tensile strength, shear strength, hardness), and chemical composition (ash, extract, lignin, total sugar content) of Korean red pine which was grown in Pyeongchang-gun, Gangwon-do, South Korea were evaluated.

• Journal of Biosystems Engineering
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• 제24권1호
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• pp.1-8
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• 1999

In this study, the physical properties of live garlic at the harvesting season were measured and analyzed as a fundamental study for developing a garlic harvester. A universal testing machine and a machine vision system were used to obtain mechanical and morphological properties of live garlic, respectively. The moisture content of live garlic at the harvesting season was 50% higher than that of dried garlic. The root of live garlic elongated greatly with respect to the applied tensile force. The relationship between the projected area and the weight of a bulb of live garlic was linear. Such a feature would be applied to develop an effective garlic harvester or garlic quality grader. Other useful physical properties of live garlic at the harvesting season were represented in the study.

• 지질공학
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• 제13권2호
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• pp.257-266
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• 2003

본 연구에서는 포천, 거창, 합천 지역에 분포하는 주라기 화강암을 대상으로 미세균열 분포특성이 화강암의 물성과 역학적 이방성에 미치는 영향에 대하여 관찰하였다. 15종의 방향성 공시체를 대상으로 한 물성시험결과를 살펴보면 공극률과 흡수율은 대체로 비례하는 것으로 측정되었다. 또한 이들 공시체를 대상으로 한 P파 속도의 분포특성을 살펴보면 hardway에 수직한 H축 방향에서 고속도이고, rift에 수직한 R축 방향에서 저속도를 보인다. 3축에 평행하게 제작된 암석 공시체를 대상으로 압축강도시험을 실시하였으며, 강도는 미세균열들의 방향별 발달정도와 밀접한 관계를 보이고 있다.