• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.7-8
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• 2006

가공배전선로의 이도는 탄성계수와 선팽계수에 따라 온도 및 장력의 변화에 대하여 다른 변화를 나타낸다. 따라서 본 연구에서는 정확한 이도설계와 선로의 장기신뢰성 확보를 위해 배전선 주요 규격에 대하여 탄성계수와 선팽창계수를 실측하여 계산값과 측정값에 어떠한 차이가 있는지를 비교하였다. 시험결과 전선의 탄성계수와 선팽창계수는 제작공정상의 여러 요인들에 의하여 영향을 받는 것으로 나타났으며, 이도설계시 탄성계수와 선팽창계수는 배전선의 측정값을 적용하는 것이 바람직 한 것으로 나타났다.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.85-96
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• 1996

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.146-154
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• 2010

The effects of severe plastic deformation, equal channel angular pressing, and annealing of Al 5052 alloy on elastic modulus have been studied. The AI 5052 alloy was plastically deformed by ECAP method after solution treatment, and then finally annealing heat treated. Elastic modulus was measured by conventional tensile and nano-indentation test, and also measured on the surface of the specimen using acoustic material signature of the acoustic microscope. The variation in the elastic modulus influenced by plastic deformation and heat treatment, inaccessible by the conventional techniques, was successfully measured by acoustic material signature and obtained the elastic modulus depending on crystal orientation at each grain.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.3-7
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• 1995

Force generated during grinding process causes elastic defomation. The effect of this deforms a workpiecs. So grinding system is explainable using the concept of macining elasticity phenomenon. Machining elasticity is defined as ratio between the true depth of c ut, and an importnat factor to affect material removal mchanism and productivity. Generally, to produce accurate surface and dimensionally precise components operators depend on their experiences. Because of these, productivity is reduced and time is wasted. The objective of this reserch is to study the effect of grinding conditions, such as table speed, depth of cut on the machining elasticity parameter.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.2
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• pp.140-148
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• 2002

Anisotropic elastic constants of Zr-2.5Nb pressure tube materials were determined by a high temperature resonant ultrasound spectroscopy (RUS). The resonant frequencies were measured using alumina wave-guides and wide band ultrasonic transducers in a small furnace. The rectangular parallelepiped specimens were fabricated along with the axial, radial and circumferential direction of the pressure tube. A nine elastic stiffness tensor for orthotropic symmetry was determined in the range of room temperature ${\sim}500^{\circ}C$. As the temperature increases, the elastic constant tensor, cij gradually decreases. Higher elastic constants along the transverse direction compared to those along the axial or radial direction are similar to the case of Young's modulus or shear modulus. A crossing of shear elastic constants along axial direction and radial direction was observed near $150^{\circ}C$. This fact corresponds to the crossing of c44 and c66 of single crystal zirconium.

• Journal of the KSME
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• v.31 no.4
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• pp.356-363
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• 1991

선형 탄성 유한요소 응력해석과 평균응력 효과를 고려한 저주기 피로실험으로부터 결정된 피로 특성, 그리고 국부변형률 방법을 종합하여 외경에 흠이 존재하는 자긴가공된 두꺼운 압력 용기의 피로수명이 평가되었다. 직사각형의 매우 날카로운 흠에서의 응력집중계수는 타원형 홈에서의 응력집중계수의 약 두배의 값이 얻어졌으며, 고강도 압력용기강인 ASTM A723의 저주기 피 로거동에 대한 평균응력 영향은 Morrow 및 SWT 파라메타를 이용하여 충분히 고려되었다. 균열발생이 예상되는 위험한 부분인 홈의 뿌리부분에서의 국부적인 응력, 변형률이 계산되었으며 예측된 피로수명은 실험적으로 얻어진 수명과 비교했을 때 2에서 4배의 오차를 보이면서 일치 하는 결과를 얻었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.520-521
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• 2007

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.549-550
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• 2006

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.26-32
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• 1998

The grinding force generated during the grinding process causes an elastic deformation of the workpiece, grinding wheel, and machine system. Thus, the true depth of cut is always smaller than the apparent depth of cut. This is known as machining elasticity phenomenon. The machining elasticity parameter is defined as a ratio between the true depth of cut and the apparent depth of cut. It is an important factor to understand the material removal mechanism of the grinding process. To increase productivity, the value of this machining elasticity parameter must be large. Therefore, it is essential to know the characteristics of this parameter. The objective of this research is to study the effect of the major grinding conditions, such as table speed and depth of cut, on this parameter experimentally. Through this research, it is found that this parameter value is increasing when the table speed is decreasing or the depth of cut is increasing. Also, this parameter value depends on the grinding mode (up grinding, down grinding).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.63-68
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• 2017

This study determines the selection of an appropriate jig material for the blade edge of the medical sapphire knife. The physical properties of the jig material affects the edge shape and chipping phenomenon in machining of the medical sapphire knife. If a grinding wheel is used, brittle workpieces such as sapphire are easily damaged by the propagation of cracks because the grinding force significantly increases. It is important to constantly maintain the grinding force in the grinding process of the brittle materials. The grinding force can be kept constantly by inducing the elastic deformation of the Jig material because the elastic deformation of brittle work-piece is negligibly low. The chipping phenomenon may be reduced by selecting the proper Jig material. Aluminum, copper, stainless steels and carbon steel were used as Jig materials. The experiment was conducted using a cast iron grinding wheel, which was installed on a conventional grinding machine with the ELID grinding system. The thickness and width of the chipping area were measured using an optical microscope and FE-SEM to analyze the shape of the blade edge. According to the experiment result, the chipping phenomenon decreased, and the sharp edge was formed when the jig materials with low elastic modulus were used.