• 전자공학회지
• /
• 제42권7호
• /
• pp.45-53
• /
• 2015

Power 소자 기술은 digital & mixed signal device와 on-chip 구현을 위해서 CMOS 공정에 대한 기본 이해가 필요하다. CMOS 공정 기반 위에 power device 공정을 추가하면서 다양한 operation voltage의 power 소자를 구현하고, passive device 들을 동일 공정에서 구현하여 다양한 components 들로 power IC 제품을 design 할 수 있도록 modular process를 제공하는 것이 중요하다. 또한 power device로 주로 사용되는 LDMOS 소자에 대한 performance 개선을 위해 simulation을 통해 key device parameter들의 특성을 예측하고, 구조를 설계하는 것이 Si process 전에 중요한 일 중의 하나이다. 아울러 power management가 potable power, consumer electronics 및 green energy에서 가장 빠르게 성장하는 분야이므로, 차별화된 power 소자 기술을 확보하여 급변하는 시장 환경에 대응하는 것이 필요하다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
• /
• pp.470-477
• /
• 2002

Possibility of passive piezoelectric damping based on a new shunting parameter estimation method is studied using finite element analysis. The adopted tuning method is based electrical impedance that is found at piezoelectric device and the optimal criterion for maximizing dissipated energy at the shunt circuit. Full three dimensional finite element model is used for piezoelectric devices with cantilever plate structure and shunt electronic circuit is taken into account in the model. Electrical impedance is calculated at the piezoelectric device, which represents the structural behavior in terms of electrical field, and equivalent electrical circuit parameters for the first mode are extracted using PRAP (Piezoelectric Resonance Analysis Program). After the shunt circuit is connected to the equivalent circuit for the first mode, the shunt parameters are optimally decided based on the maximizing dissipated energy criterion. Since this tuning method is based on electrical impedance calculated at piezoelectric device, multi-mode passive piezoelectric damping can be implemented for arbitrary shaped structures.

• Structural Engineering and Mechanics
• /
• 제37권4호
• /
• pp.443-458
• /
• 2011

An extensive numerical investigation on the magnetorheological (MR) damper-based smart passive control system for mitigating vibration of stay cables under wind loads has been conducted. The smart passive system is incorporated with an electromagnetic induction (EMI) device for reducing complexity of the conventional MR damper based semi-active control system by eliminating an external power supply part and a feedback control part (i.e., sensors and controller). In this study, the control performance of the smart passive system has been evaluated by using a cable structure model extracted from a full-scale long stay cable with high tension. Numerical simulation results of the proposed smart damping system are compared with those of the passive and semi-active control systems employing MR dampers. It is demonstrated from the results that the control performance of the smart passive control system is better than those of the passive control cases and comparable to those of the semi-active control systems in the forced vibration analysis as well as the free vibration analysis, even though there is no external power source in the smart passive system.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권4호
• /
• pp.249-257
• /
• 2000

In this paper, we propose the use of stochastic finite element method, that is popularly employed in mechanical structure analysis, for more practical designing purpose of RF device. The proposed method is formulated based on the vector finite element method cooperated by pertubation analysis. The method utilizes sensitivity analysis algorithm with covariance matrix of the random variables that represent for uncertain physical quantities such as length or various electrical constants to compute the probabilities of the measure of performance of the structure. For this computation one need to know the variance and covariance of the random variables that might be determined by practical experiences. The presenting algorithm has been verified by analyzing several device with different be determined by practical experiences. The presenting algorithm has been verified by analysis several device with different measure of performanes. For the convenience of formulation, two dimensional analysis has been performed to apply it into waveguide with dielectric slab. In the problem the dielectric constant of the dielectric slab is considered as random variable. Another example is matched waveguide and cavity problem. In the problem, the dimension of them are assumed to be as random variables and the expectations and variances of quality factor have been computed.

• 조명전기설비학회논문지
• /
• 제25권1호
• /
• pp.101-106
• /
• 2011

The failure of cooling system in Superconducting Fault Current Limiter(SFCL) increases the impedance of superconducting device, and due to malfunction of inner switches the SFCL opens the distribution system inadvertently when required to do so. In this paper, the ground fault and short circuit fault were classified as active failure and the open circuit fault was passive failure. A reliability model of SFCL considers the passive failure as well as active failure, and in the case study the reliability indices of distribution system are evaluated. It is possible that the reliability evaluation excluded passive failure makes the customers reliability seem so worse than it really was. Therefore, the reliability models of SFCL must include the active failure and passive failure together to evaluate the reliability of distribution system connected SFCL.

• 한국공간구조학회논문집
• /
• 제12권1호
• /
• pp.99-108
• /
• 2012

본 연구에서는 지진하중을 받는 대공간 구조물의 지진응답을 저감시키기 위하여 돔 구조물에 대한 동조질량제어장치(TMD)의 적용성을 검토하였다. 이를 위하여 돔 구조물의 기본적인 동적특성을 가지고 있으며 가장 간단한 구조이기도 한 스타 돔 구조물에 수동형 TMD를 설치하여 지진응답 제어성능을 평가하였다. 본 연구에서는 KBC2009에 따른 인공 지진하중을 수평방향과 연직방향으로 가하여 스타 돔 구조물에 대한 지진응답을 분석하였으며 이를 바탕으로 TMD의 설치에 따른 스타 돔 구조물의 지진응답 제어성능을 분석하였다. 해석결과 다음과 같은 결론을 얻을 수 있었다. 지진하중의 방향에 반응하는 스타 돔 구조물의 진동모드 분석을 통하여 수동 TMD를 설치하는 것이 지진응답 제어에 있어서 효과적인 것을 확인할 수 있었다.

• 한국ITS학회 논문지
• /
• 제7권5호
• /
• pp.97-105
• /
• 2008

반도체 공정의 미세화 및 마이크로 시스템 기술의 발전 그리고 소형 무선PAN 및 이동통신 장치들의 급증으로 인하여 전자부품들의 소형화와 직접화에 대한 요구가 지속적으로 증가되고 있다. 본 연구에서는 휴대형 무선PAN 및 이동통신용 전자회로 설계에 다양한 목적으로 널리 사용되고 있는 기저대역의 수동소자들 중 미세 커패시터의 안정성과 전기적 특성을 확보하기 위하여, 유전체인 AIN을 사용하여 MIM구조로 제작된 미세 박막 커패시터 소자의 전기적인 특성을 분석하고 기저대역에서의 성능을 평가한다. 또한 제작된 미세 박막형 커패시터의 용량제어 방법을 제시함으로서 기저대역에서 범용으로 사용할 수 있는 미세 박막 커패시터의 모델을 제시하고자 한다. 또한, 주파수 대역에 따른 MIM구조의 AIN 커패시터 특성을 분석함으로서 향후 임베디드 소자와 집적화를 위한 고정밀의 미세수동 소자로서의 활용방안을 제시하고자한다.

• 한국전자파학회논문지
• /
• 제11권2호
• /
• pp.268-277
• /
• 2000

이동통선 서비스가 확장됨에 따라 인접 기지국간의 간섭이 증가하고 그에 따른 IMD(Intermodulation Distortion) 문제도 증가하여 Active IMD뿐만 아니라 Passive IMD(Passive Intermodulation Distortion)에 대한 문 제도 함께 부상하고 었다. 따라서 본 고에서는 대표적인 RF 소자 중 동축선에서의 PIMD의 발생기구의 분석을 위하여 다양한 도금 두께와 도금 재질을 갖는 어랩터를 설계 및 제작하였다. 제작된 어댐터 측정결과 1M 발생 수준이 도금 재질의 전도율, 소자의 구조, 도금 재질의 두께. Aging현상 등에 의존함을 확인하였으며, 도금 두께의 변화와 재질의 변화를 통해 PIMD 발생기구를 분석하였고, PIMD의 제어기술 방안을 검토하였다.

• Smart Structures and Systems
• /
• 제24권1호
• /
• pp.141-155
• /
• 2019

This work evaluates the influence of negative stiffness on the performances of various vehicle suspension systems, and proposes a re-centering negative stiffness device (NSD). The re-centering NSD consists of a passive magnetic negative stiffness spring and a positioning shaft with a re-centering function. The former produces negative stiffness control forces, and the latter prevents the amplification of static spring deflection. The numerical simulations reveal that negative stiffness can improve the ride comfort of a vehicle without affecting its road holding abilities for either passive or semi-active suspension systems. In general, the improvement degree of ride comfort increases as negative stiffness increases. For passive suspension system, negative stiffness brings in negative stiffness feature in the control forces, which is helpful for the ride comfort of a vehicle. For semi-active suspensions, negative stiffness can alleviate the impact of clipped damping in semi-active dampers, and thus the ride comfort of a vehicle can be improved.

• 대한물리의학회지
• /
• 제17권3호
• /
• pp.79-86
• /
• 2022

PURPOSE: By virtue of its location, the iliopsoas muscle has the potential to affect the function of the diaphragm. Therefore, the purpose of this study was to investigate the effects of passive stretching of the iliopsoas muscles on pulmonary function. METHODS: Twenty male university students participated in this study. Subjects with low back pain, negative results on the modified Thomas test, and chest breathing patterns not directly related to the function of the iliopsoas muscles were excluded from this study. A digital pulmonary function measuring device (Pony FX, COSMED Inc, Italy) was used to test pulmonary function. The test was performed three times: the first test before passive stretching, the second test 10 minutes after the first test, and the third after passive stretching. Passive stretching was performed 5 times for each of the left and right iliopsoas muscles. Passive stretching was carried out for 20 seconds followed by a 10-second break. The SPSSWIN (ver. 27.0) statistics program was used for data analysis, and the significance level was α =.05. RESULTS: Among slow vital capacity (SVC) parameters, tidal volume (VT), inspiratory reserve volume (IRV), inspiratory capacity (IC) and vital capacity (VC) improved significantly after passive stretching. Also, among the maximal effort vital capacity (MEVC) parameters, forced vital capacity(FVC) and forced expiratory volume in one second(FEV1) improved significantly after passive stretching. CONCLUSION: The results showed that among the various pulmonary function parameters measured, passive stretching of the iliopsoas muscles can improve the SVC and MEVC. Therefore, passive stretching of the iliopsoas muscles may be considered for use as a treatment method to improve pulmonary function.