• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.319-322
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• 1999

In order to accurately measure the high voltage of 22.9[kV] power distribution lines, we investigated the temperature dependence of measuring voltage for single element and stack elements(22, 44, 66 layers, respectively). When one line voltage is 13, 20O[V], the error of measuring voltage with temperature(-25[$^{\circ}C$]~50[$^{\circ}C$]) was decreased with increasing of stack number and stack element with 66 layers was the least error of ${\pm}0.87%$.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.66-68
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• 2014

The paper deals with the vibration characteristics of the stack transducers made of piezoelectric discs with different radius. Natural frequencies of the stack transducers were evaluated by finite-element analysis. The natural frequencies of the analysis results were compared with those of each piezoelectric disc, and their relations were investigated.

• 한국전기전자재료학회논문지
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• 제13권5호
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• pp.396-401
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• 2000

In order to accurately measure the high voltage of 22.9[kV] power distribution lines we investigated the temperature dependence of measuring voltage on the number of stack layers in the voltage measurement system made from single and stack voltage divider capacitors (22, 44, 66 layers, respectively). Temperature coefficient of dielectric constant(TC$\varepsilon_{{\gamma}}$/)of voltage divider capacitors which were fabricated by BaTi $O_3$system ceramics showed the variations from -2.28% to +1.69% in the range of -25[$^{\circ}C$] ~50[$^{\circ}C$]) was decreased with increasing of stack number and the stack element of 66 layers showed the least error of $\pm$0.87%or of $\pm$0.87%.

• 제어로봇시스템학회논문지
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• 제15권8호
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• pp.798-803
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• 2009

This paper proposes a grating scanner which is driven by a stack-type piezoelectric element. The mechanism of the grating scanner is based on flexure hinges. Using some constraints, the compliant mechanism is designed and then verified by Finite Element Analysis. The designed compliant mechanism is manufactured by wire electro-discharge machining, and then integrated with a stack-type piezoelectric element for actuation and a capacitance displacement sensor for measuring ultra-precision displacement. Experiments demonstrates the characteristics and the performances of the grating scanner using the terms of working range, resonance frequency, bandwidth and resolution. The grating scanner is applicable to a Moire interferometry for measuring 3-dimensional microscopic surface.

• 한국정밀공학회지
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• 제24권12호
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• pp.88-94
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• 2007

A flexure hinge-based compliant stage driven by stack-type piezoelectric elements has high precision motion but small operational range due to the characteristics of the piezoelectric element. Since the common flexure hinges can be broken by excessive deflection when the displacement is amplified by a high amplification ratio, a flexure hinge mechanism for large deflection is required. A cartwheel-type flexure hinge has an advantage of larger deflection compared with the common flexure hinges. This study presents a rotation stage with cartwheel-type flexure hinges driven by a stack-type piezoelectric element. The characteristics and the performance of the rotation stage are described by the terms of principal resonance frequency, amplification ratio of rotational displacement, maximum rotational displacement and block moment, in which the terms are analyzed by geometric parameters of the rotation stage. The analyzed results will be used as the guideline of the design of the rotation stage.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.101-106
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• 1999

Fiber reinforced plastic composites is widely used to make be lightening of aircraft and automotive owing to having high specific strength and specific modulus. And it is very important to know a charge shape in order to have good products in the compression molding. In particular, the product such as a bumper beam is composed of the random and unidirectional composite mats. Its deformation and charge shape are very different by stack type of random and unidirectional mats. In this paper, the characteristics of flow fronts such as a bulging phenomenon for step-type random/unidirectional composite mats and slip parameters are studied numerically. And the effects of viscosity ratio and stack type on the mold filling parameters are also discussed.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.175-178
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• 2003

Mechanical behavior of a fuel stack was studied by the orthotropic material model. The fuel stack is mainly composed of bipolar plate (BP), gasket, end plate, membrane electrolyte assembly (MEA), and gas diffusion layer (GDL). Each component is fastened with a suitable pressure. It is very important to maintain a suitable contact pressure of BP, because it affects the efficiency of the fuel cell. This study compared mechanical behavior of various fastening types of the fuel cell stack. Bar, band, and modified band fastening type are used. The band fastening type showed that it reduces total volume of the cell, but it does not improve the contact pressure distribution of each BP. The modified band fastening type was designed by considering the deformations of band fastening type, and it showed a good enhancement of contact pressure distribution.

• 한국주조공학회지
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• 제40권3호
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• pp.76-84
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• 2020

The effects of Alloying Element and Heat Treatment on the mechanical properties of ductile cast iron poured into shell stack molds were investigated. The strength and hardness were increased and the elongation was decreased roughly with the increased amounts of tin and copper added, respectively. Those were greatly increased with the increased amount of tin added and the elongation was roughly decreased with it. In the simultaneous addition of copper and tin, the strength and hardness of the tin increased, but the elongation rate decreased. Those were greatly increased and this was decreased with normalizing. In the case of specimens with smaller section sizes during austempering processing, the strength and hardness were higher than those with larger sections, but the elongation rate was lower.

• 한국결정성장학회지
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• 제26권4호
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• pp.139-144
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• 2016

Tonpilz 트랜스듀서의 거동에 미치는 압전 소재의 형상과 크기의 효과에 대하여 유한요소법을 통한 컴퓨터 모사를 통하여 연구하였다. 도넛 형태의 압전체의 직경과 높이 그리고 쌓아올린 stack의 수를 변수로 고려하였고 최종적으로 소재 자체를 특성이 뛰어난 단결정 소재로 변환하였을 때 그 특성인 출력과 TVR 대역폭이 어떻게 변하는지를 모사하였다. 그 결과, 리랙서 단결정을 활용함으로써 같은 구조에서 출력을 10배 정도 향상시킬 수 있음을 확인하였다.

• 한국주조공학회지
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• 제40권2호
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• pp.25-33
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• 2020

The effects of mold variable and main alloying element on the mechanical properties of ductile cast iron poured into shell stack mold were investigated. The strength and hardness of with the smaller cross-section of the diameter of 6.25mm were higher than those of 12.50mm. On the other hand, the elongation of the former was lower than that of the latter. The strength and hardness of the specimens obtained from the center layer in the 5-story stack mold were the lowest and those for other specimens were increased with increased distance from the center. The elongation of those were the highest of all. The strength and hardness of the specimens obtained from the center layer were decreased the elongation was increased with the increased number of layers. The strength and hardness were increased and the elongation was decreased roughly with the increased amounts of reaidual magnesium and carbon content added, respectively. The strength and hardness were increased and the elongation was decreased roughly with the increased amounts of silicon content added to 2.45wt% and rather decreased with that to 2.85wt%. The effect of silicon content showed the opposite tendency to those of residual magnesium and carbon content.