• JSTS:Journal of Semiconductor Technology and Science
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• 제2권4호
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• pp.259-267
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• 2002

We present a novel 3D fabrication method with single X-ray process utilizing an X-ray mask in which a micro-actuator is integrated. An X-ray absorber is electroplated on the shuttle mass driven by the integrated micro-actuator during deep X-ray exposures. 3D microstructures are revealed by development kinetics and modulated in-depth dose distribution in resist, usually PMMA. Fabrication of X-ray masks with integrated electrothermal xy-stage and electrostatic actuator is presented along with discussions on PMMA development characteristics. Both devices use $20-\mu\textrm{m}$-thick overhanging single crystal Si as a structural material and fabricated using deep reactive ion etching of silicon-on-insulator wafer, phosphorous diffusion, gold electroplating, and bulk micromachining process. In electrostatic devices, $10-\mu\textrm{m}-thick$ gold absorber on $1mm{\times}1mm$ Si shuttle mass is supported by $10-\mu\textrm{m}-wide$, 1-mm-long suspension beams and oscillated by comb electrodes during X-ray exposures. In electrothermal devices, gold absorber on 1.42 mm diameter shuttle mass is oscillated in x and y directions sequentially by thermal expansion caused by joule heating of the corresponding bent beam actuators. The fundamental frequency and amplitude of the electrostatic devices are around 3.6 kHz and $20\mu\textrm{m}$, respectively, for a dc bias of 100 V and an ac bias of 20 VP-P (peak-peak). Displacements in x and y directions of the electrothermal devices are both around $20{\;}\mu\textrm{m}$at 742 mW input power. S-shaped and conical shaped PMMA microstructures are demonstrated through X-ray experiments with the fabricated devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.163-163
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• 2012

We observed strain evolution of P3HT crystals in P3HT:PCBM films and the effect of Al electrode on the evolution during real time annealing process. Based on simple assumptions, both relaxed lattice parameters and thermal expansion coefficient could be quantitatively determined. P3HT:PCBM films displayed tensile strain in as-prepared samples regardless of the presence of an Al layer. In the absence of Al layer, P3HT crystals showed only strain relaxation at an annealing temperature of $180^{\circ}C$. Meanwhile In the presence of an Al layer, the strain was relaxed and changed to compressive strain at around 120C annealing temperature, which indicated a tightening of the thiophene ring packing. These behaviors support the improved performance of devices fabricated by post annealing process.

• 한국세라믹학회지
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• 제30권2호
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• pp.107-114
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• 1993

Zinc-Borosilicate(ZnO 65.0wt%, B2O3 21.5wt%, SiO2 9.0wt%, PbO or tiO2 4wt%) passivation glasses were studied using differential thermal analysis(DTA), scanning electron microscopy(SEM) observations, X-ray diffraction (XRD) patterns and measurement of thermal expansion coefficients. Passivation glasses containing 4wt% TiO2 and 4wt% PbO had crystallization temperature of 680~73$0^{\circ}C$ and major crystalline phases were identified by X-ray diffraction as $\alpha$-ZnO.B2O3 and $\alpha$-5ZnO.2B2O3. As increasing firing temperature, the size of crystalline phases increased by observation of SEM. The thermal expansion coefficient of crystallized glass frits was smaller than that of unfired glass.

• 마이크로전자및패키징학회지
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• 제24권1호
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• pp.35-43
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• 2017

The three-dimensional integrated circuit (3D-IC) is a general trend for the miniaturized and high-performance electronic devices. The through-silicon-via (TSV) is the advanced interconnection method to achieve 3D integration, which uses vertical metal via through silicon substrate. However, the TSV based 3D-IC undergoes severe thermo-mechanical stress due to the CTE (coefficient of thermal expansion) mismatch between via and silicon. The thermo-mechanical stress induces mechanical failure on silicon and silicon-via interface, which reduces the device reliability. In this paper, the thermo-mechanical reliability of TSV based 3D-IC is reviewed in terms of mechanical fracture, heat conduction, and material characteristic. Furthermore, the state of the art via-level and package-level design techniques are introduced to improve the reliability of TSV based 3D-IC.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.629-631
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• 2012

안드로이드 시스템의 경우 고정된 네트워크 하드웨어 기반의 모바일 시스템 OS로서 네트워크 확장에 어려움이 있다. 이런 안드로이드 OS를 스마트 TV OS로 사용하기 위한 무선네트워크 확장은 필수적이라 볼 수 있다. 본 연구에서는 이런 제한적 하드웨어 지원의 모바일용 안드로이드 OS의 USB 기반 WIFI 모듈과 같은 외장 네트워크 장치를 통한 네트워크 확장에 관해 연구한다.

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1060-1069
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• 2005

Silencers are engineering devices that are designed to attenuate sound waves propagating in a flowing medium. The muffler type silencer has a series of chambers in parallel or series utilizing the reflection and expansion characteristics of the expansion chambers, sidetubes, branch resonators, and tailpipes to attenuate the sound. To Improve the performance of industrial blower silencer of muffler type which is employed in petrochemical plant, this paper seeks its optimal arrangement of buffs by experimental method and suggests optimal arrangement of buffs. Experimental results show that the optimal one suggested can reduce the noise level as much as 14 dB (or 18 dB(A)) in the laboratory and as much as 4 dB(A) compared to that of the existing silencer on the ground.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.177-183
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• 2008

For 10 kW-class Stirling engine using scroll expander and scroll compressor, considerations on thermal expansion of the fixed and orbiting scroll members of the scroll expander due to high gas temperature at the expander inlet has resulted in adopting of the keys between the fixed scroll and main frame for the fixed scroll side and spring type insertion between the orbiting scroll base plate and supporting holders for orbiting scroll side. Dynamic analysis on the fixed and orbiting scroll members and the shafts of the scroll expander showed that using of these devices for complying thermal expansion caused large variations of the forces acting on the fixed scroll keys and on the power transmitting shafts and also on the shaft bearings.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.587-592
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• 2006

This paper presents expansion and contraction in accordance with temperature change of contact wire and messenger wire. The tensioning device is designed and installed to pull the contact wire and messenger wire straight at all times. Pulling a contract wire straight ensures that smooth contract is maintained between the contact wire and pantograph of an electric train, and this makes it possible to ensure a stable supply of electricity to the train. Normally, tensioning devices are installed at two positions over a distance of 1.0[km] to 1.6[km] per line. In installing the tensioning device, therefore, it is necessary to study the stroke(the range of the extension/contraction rate of the tensioning device compatible with that of the contact wire and messenger wire due to change in temperature). This paper introduces and discusses this topic.

• 한국전기전자재료학회논문지
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• 제25권10호
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• pp.798-804
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• 2012

This paper focuses on thermal properties of a newly prepared composite material by nano-silica and micro-silica mixture. Nano-silica and micro-silica mixture composites were made by dispersing surface treated nano-silica(average radius: 10 nm) and micro-size silica in epoxy resin. To investigate the effects of nano-silica and micro-size silica mixture(ENMC), the glass transition temperature (Tg), coefficients of thermal expansion(CTE) and elastic modulus of DMA properties by DSC, TMA and DMA devices were measured for the ENMC according to increase nano-silica addition contents and EMC. All properties of the neat epoxy were improved by the addition of micro-silica, which was improved much further by the addition of surface treated nano-silica to the EMC system.

• The Journal of Advanced Prosthodontics
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• 제4권4호
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• pp.227-234
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• 2012

PURPOSE. The aims of this pilot study were to introduce implant loading devices designed for animal study and to evaluate the validity of the load transmission ability of the loading devices. MATERIALS AND METHODS. Implant loading devices were specially designed and fabricated with two implant abutments and cast metal bars, and orthodontic expansion screw. In six Beagles, all premolars were extracted and two implants were placed in each side of the mandibles. The loading device was inserted two weeks after the implant placement. According to the loading protocol, the load was applied to the implants with different time and method, simulating early, progressive, and delayed loading. The implants were clinically evaluated and the loading devices were removed and replaced to the master cast, followed by stress-strain analysis. Descriptive statistics of remained strain (${\mu}{\varepsilon}$) was evaluated after repeating three cycles of the loading device activation. Statistic analysis was performed using nonparametric, independent t-test with 5% significance level and Friedman's test was also used for verification. RESULTS. The loading devices were in good action. However, four implants in three Beagles showed loss of osseointegration. In stress-strain analysis, loading devices showed similar amount of increase in the remained strain after applying 1-unit load for three times. CONCLUSION. Specialized design of the implant loading device was introduced. The loading device applied similar amount of loads near the implant after each 1-unit loading. However, the direction of the loads was not parallel to the long axis of the implants as predicted before the study.