• Advances in nano research
• /
• v.15 no.3
• /
• pp.263-275
• /
• 2023

The electron transport properties of Y-type zigzag branched carbon nanotubes (CNTs) are of great significance for micro and nano carbon-based electronic devices and their interconnection. Based on the semi-empirical method combining tight-binding density functional theory and non-equilibrium Green's function, the electron transport properties between the branches of Y-type zigzag branched CNT are studied. The results show that the drain-source current of semiconducting Y-type zigzag branched CNT (8, 0)-(4, 0)-(4, 0) is cut-off and not affected by the gate voltage in a bias voltage range [-0.5 V, 0.5 V]. The current presents a nonlinear change in a bias voltage range [-1.5 V, -0.5 V] and [0.5 V, 1.5 V]. The tangent slope of the current-voltage curve can be changed by the gate voltage to realize the regulation of the current. The regulation effect under negative bias voltage is more significant. For the larger diameter semiconducting Y-type zigzag branched CNT (10, 0)-(5, 0)-(5, 0), only the value of drain-source current increases due to the larger diameter. For metallic Y-type zigzag branched CNT (12, 0)-(6, 0)-(6, 0), the drain-source current presents a linear change in a bias voltage range [-1.5 V, 1.5 V] and is symmetrical about (0, 0). The slope of current-voltage line can be changed by the gate voltage to realize the regulation of the current. For three kinds of Y-type zigzag branched CNT with different diameters and different conductivity, the current-voltage curve trend changes from decline to rise when the branch of drain-source is exchanged. The current regulation effect of semiconducting Y-type zigzag branched CNT under negative bias voltage is also more significant.

• Steel and Composite Structures
• /
• v.24 no.2
• /
• pp.141-149
• /
• 2017

In this study, vibration analysis of fluid conveying microbeams under non-ideal boundary conditions (BCs) is performed. The objective of the present paper is to describe the effects of non-ideal BCs on linear vibrations of fluid conveying microbeams. Non-ideal BCs are modeled as a linear combination of ideal clamped and ideal simply supported boundary conditions by using the weighting factor (k). Non-ideal clamped and non-ideal simply supported beams are both considered to show the effects of BCs. Equations of motion of the beam under the effect of moving fluid are obtained by using Hamilton principle. Method of multiple scales which is one of the perturbation techniques is applied to the governing linear equation of motion. Approximate solutions of the linear equation are obtained and the effects of system parameters and non-ideal BCs on natural frequencies are presented. Results indicate that, natural frequencies of fluid conveying microbeam changed significantly by varying the weighting factor k. This change is more remarkable for clamped microbeams rather than simply supported ones.

• Journal of the Korean Home Economics Association
• /
• v.44 no.3 s.217
• /
• pp.115-126
• /
• 2006

The purpose of this study was to propose theoretical-practical strategies of family-based intervention for the "Healthy Family-Support Center." The theoretical background used was an ecological approach, that is, taking viewpoints of client family's microsystems as well as those of exo- and macrosystems. This study raised several critical points in researching and developing family-based intervention programs. Based on a review of the literature, the study indicated why an ecological, family-based intervention model was a relevant alternative to investigate issues in family welfare and to deliver possible assistance and solutions for them.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.8
• /
• pp.152-156
• /
• 2004

A new tool of surface patterning technique for general purpose lithography was developed based on shadow mask method. This paper describes the fabrication of a new type of miniaturized shadow mask. The shadow mask is fabricated by photolithography and etching of 100-mm full wafer. The fabricated shadow mask has over 388 membranes with apertures of micrometer length scale ranging from 1${\mu}{\textrm}{m}$ to 100s ${\mu}{\textrm}{m}$ made on each 2mm${\times}$2mm large low stress silicon nitride membrane. It allows micro scale patterns to be directly deposited on substrate surface through apertures of the membrane. This shadow mask method has much wider choice of deposit materials, and can be applied to wider class of surfaces including chemical functional layer, MEMS/NEMS surfaces, and biosensors.

• IT SoC Magazine
• /
• s.19
• /
• pp.24-28
• /
• 2007

올해 44회를 맞이한 DAC(Design Automation Conference)는 6월 4일부터 8일까지 5일간 캘리포니아 샌디에고에서 개최되었다. 이번 DAC에도 샌프란시스코에서 열렸던 43회 DAC와 마찬가지로 인텔, IBM, ARM, Sun Microsystems 등 첨단 SoC/IP 설계회사와 Cadence, Synopsys 등 EDA 개발회사, 그리고 TSMC, UMC 등 유수의 파운드리회사들이 참가하였다. 전시회 참여업체는 약 250여개로 예년보다 약간 증가하였고 총 참관객수는 11,000여명으로 다소 줄어들었다. 하지만 국내 참여업체 관계자들은 참관객들의 질적인 수준이 작년 DAC보다 더 높아 제품을 홍보하고 관련 업계 사람들과 정보를 교환하기에 더없이 좋은 기회였다고 평가했다. 또한 이번 DAC 컨퍼런스는 총 10개 트랙, 53개의 세션들이 진행되었으며 약 161개의 논문이 발표되어 매우 역동적인 기술교류가 이루어졌다. 여기에서는 44th DAC의 주요 이슈와 전시회에 참여하였던 국내 SoC업체들의 제품에 대해 살펴 보고자한다.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.741-745
• /
• 2007

Supplying power to microsystems that have no physical connection to the outside is difficult, and using batteries is not always appropriate. This paper discusses how to generate electricity from mechanical energy when vibrated in a cantilever beam. A model for the system predicts that the output power of the system is maximized when the mechanical damping in the system is minimized. Furthermore, to cover a wide frequency range and to be useful in a number of applications, a system of beams with different resonant frequencies has been designed and optimized. This information makes it possible to determine what design alternatives are feasible for the creation of a micro power supply for any specific application of MEMS.

• 한국초전도학회:학술대회논문집
• /
• v.9
• /
• pp.38-42
• /
• 1999

We prepared hish T$_c$ Josephson junctions that have different I$_c\;'s$ and R$_n\;'s$ and studied their microwave properties. We measured the current-voltage characteristics of the junctions under the irradiation of 22 GHz electromagnetic wave at various temperatures. from the Shapiro steps, we calculated the maximum detectable frequency and the microwave received power of the junctions. Increasing critical current values increase both maximum detectable frequency and sensitivity. However, increasing temperature increase sensitivity but decrease maximum detectable frequency.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.5
• /
• pp.178-182
• /
• 2007

This study represents the efficient depth measurement for 3-dimensional microsystems using the disparity histogram from stereo images. Implementation of user-friendly Windows program written in C++ involves the various methods for the stereo-image processing in which the minimization of matching-pixel error upon the unique point for stereo images was carried out as a pre-processing method. Even though MPC among various methods was adopted in the present measurement, the resulting measurements seem to require optimizations of the windows sizes and corrections of post-manipulation for stereo images. The present work using Windows program is promising to measure the 3-dimensional depth of micro-system efficiently in implementing the 3-dimensional structure of micro-systems.

• International Journal of Vascular Biomedical Engineering
• /
• v.4 no.2
• /
• pp.1-6
• /
• 2006

Microsystems create new opportunities for conventional cell analysis by combining microfluidics and flow cytometry. This article describes recent developments in conventional flow cytometers and related microfluidic flow cytometers to detect, analyze, and sort cells or particles. Flow cytometry strongly consisted of fluidics, optics and electronics requires a large space to equip various components, which are mostly the fluidic components such as compressor, fluid handling system. Adopting microfluidics into flow cytometry enables volume- and power-efficient, inexpensive and flexible analysis of particulate samples. In this paper, we review various efforts that take advantage of novel techniques to build microfluidic cell analysis systems with high-speed analytical capability. Highly integrated microfluidic cytometry shows great promise for basic biomedical and pharmaceutical research, and robust and portable point-of-care devices could be used in clinical settings.

• Proceedings of the IEEK Conference
• /
• 2003.11b
• /
• pp.65-68
• /
• 2003

In this paper, we consider issues related to the autonomous management of a server cluster Server clustering technique is widely used for high available Internet servers such as a web server, because it provides very scalable and reliable service. However, it is very burden-some to manage the cluster system. For instance, installation or configuration of a new node requires skilled administrators. Also, when a node is failed, it should be recognized and recovered by a human. The management complexity gets higher while increasing the number of machines for higher throughput. Here, we are going to alleviate the management complexity by building an autonomous cluster server with Jini $_{TM}$ technology from Sun Microsystems.