• Journal of Korea Water Resources Association
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• v.33 no.4
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• pp.385-392
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• 2000

An experimental investigation was conducted to determine the effect of a nonuniform pier on the stability of riprap placed around bridge piers. A nonuniform pier is one of which the cross-sectional dimension varies over the length of the pier and comprises a cylinder of diameter bp placed on a larger diameter of foundation bf. and the stability of riprap are significantly influenced by the height of foundation z. The critical height of foundation is defined as the height of foundation which has the same critical velocity to that of uniform pier without foundation, and it was found to be zc=0.8bf. For z

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.7
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• pp.604-610
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• 2004

Ultraviolet-nanoimprint lithography (UV-NIL) is a promising method for cost-effectively defining nanoscale structures at room temperature and low pressure. Since the resolution of transferred nanostructures depends strongly upon that of nanostamps, the nanostamp fabrication technology is a key technology to UV-NIL. In this paper, a $5\times5\times0.09$ in. quartz stamp whose critical dimension is 377 nm was fabricated using the etching process in which a Cr film was employed as a hard mask for transferring nanostructures onto the quartz plate. To effectively apply the fabricated 5-in. stamp to UV-NIL on a 4-in. Si wafer, we have proposed a new UV-NIL process using a multi-dispensing method as a way to supply resist on a wafer. Experiments have shown that the multi-dispensing method can enable UV-NIL using a large-area stamp.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.316.2-316.2
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• 2016

Device가 점점 Shrinkage 됨에 따라 미세 패터닝을 위하여 기존에 사용하던 박막은 Hardmask 로써 CD(Critical Dimension)가 제한적으로 이를 개선하기 위한 비정질 실리콘 (amorphous silicon)으로 대체하여 사용되는 Layer의 수가 증가하고 있다. 하지만 비정질 실리콘을 증착 시, 하부막에 따른 Adhesion 및 Hillocks과 같은 공정상에서 발생하는 문제들이 발생하게 되는데, 이는 소자의 특성을 떨어뜨리게 된다. 이러한 문제를 해결하고자 본 연구에서는 PECVD를 사용하여 비정질 실리콘 박막을 증착하였고, 그 특성을 분석하였으며, Adhesion 및 Hillock 개선을 위해 비정질 실리콘 박막 증착 전 처리를 최적화하여 특성을 개선하였다. 증착된 박막의 두께 및 굴절률은 Auto thickness measurement로 분석하였고, 표면 특성은 Field emission scanning electron microscopy(FE-SEM 그림 참고), 4 Point Bending TEST를 이용하여 분석을 수행하였다.

• Journal of the East Asian Society of Dietary Life
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• v.1 no.3
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• pp.305-311
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• 1991

The study was designed to investigate overall acceptability of rice extrudate with added ginseng flour extruded by single screw extruder. Graphic three dimension analysis on response surface regression was conducted for overall acceptability evaluated by balanced incomplete block design. Overall acceptability, which formed a saddle point, increased as moisture content increased at lower die temperature, and as moisture content decreased at higher die temperature. Critical values of each variable which indicated optimum response are 5.0% ginseng content, 17.8% moisture content and 104.6$^{\circ}C$ die temperature, and optimum inferred score of overall acceptability is 59.6 and 90. Key words: extrdate, overall acceptability, response surface regression analysis, balanced incomplete block method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.1
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• pp.88-94
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• 2006

A typical disk brake system consists of caliper housing, piston, seal and two pads etc. The configuration of seal groove, dimension of piston and seal, and seal material properties are important ones for brake performance, as these affect the retraction of piston. The rubber seal is designed to perform dual functions of sealing the brake oil at brake-applied and retracting the caliper piston at brake-released. In this paper, the seal stress is analyzed using Finite Element Method and experiment is conducted by Taguchi's Method. We attempt to quantify the critical design factors in the seal groove and evaluate their impact on some of brake performance factors. The investigation obtained from this study can not only enhance the seal groove design optimization, but also reduce product prototype testing and development time.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.160-160
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• 2003

This paper describes some of the key issues associated with the patterning of metal electrodes of sub-micron (especially at the critical dimension (CD) of 0.15 $\mu\textrm{m}$) dynamic random access memory (DRAM) devices. Due to reactive ion etching (RIE) lag, the Pt etch rate decreased drastically below the CD of 0.20 $\mu\textrm{m}$ and thus the storage node electrode with the CD of 0.15 $\mu\textrm{m}$ could not be fabricated using the Pt electrodes. Accordingly, we have proposed novel techniques to surmount the above difficulties. The Ru electrode for the stack-type structure is introduced and alternative schemes based on the introduction of the concave-type structure using Pt or Ru as an electrode material are outlined.

• Journal of the Korean Vacuum Society
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• v.5 no.2
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• pp.169-174
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• 1996

The applications of the high density plasma sources to the etching in semiconductor fabrication process are actively studied because of the more strict requirement from the dry etching process due to shrinking down of the critical dimension. But in the oxide etching with the high density plasma sources, abundant fluorine atoms released from the flurocarbon feed gas make it difficult to get the highly selective $SiO_2/Si$ etching. In this study, to improve the $SiO_2/Si$ etch selectivity through the control of the radical loss channels, we propose the wall heating , one of methods of controlling loss mechanisms. With appearance mass spectroscopy(AMS) and actinometric optical emission spectroscopy(OES), the increase of both radicals impinging on the substrate and existing in bulk plasma, and the decrease of the fluorine atom with wall temperature are observed. As a result, a 40% improvement of the selectivity was achieved for the carbon rich feed gas.

• Geotechnical Engineering
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• v.7 no.1
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• pp.53-68
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• 1991

This paper aims at the investigation of various seepage behavior when rainfall infiltarates into unsaturated ground and understanding of the mechanism for slope instability due to rainfall. For this purpose an experimental study is carried out for model slopes using the test equipment which can simulate various rainfall intensity. In addition, a numerical study is performed for the same dimension and boundary condition as the experimental model. From both the experimental test and numerical analysis the progress of wetting front with time, critical amounts of rainfall, and pore-water pressure development with time are know in detail and their effects on slope stability are described.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1270-1273
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• 2004

The combination of methane-chemical activation and Self-propagating High-temperature synthesis (SHS) has widened the possibilities for both methods. For YBCO systems the investigation showed that a short-term mechano-chemical activation of initial powders before SHS leads to single-phase and ultra-fine products. A new technique for preparation ultra-fine high-temperature superconductors of YBCO composition with a grain size d < $1{\mu}m$ is developed. The specific feature of the technique is formation of the $YBa_2Cu_3O_{7-x}$ crystalline lattice directly from an X-ray amorphous state arising as a result of mechanical activation of the original oxide mixture. The technique allows the stage of formation of any intermediate reaction products to be ruled out. X-ray and magnetic studies of ultra-fine high temperature superconductors (HTS) are carried out. Dimension effects associated with the microstructure peculiarities are revealed. A considerable enhancement of inter-grain critical currents is found to take place in the ultra-fine samples investigated.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.46.5-46
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• 2002

As device dimension shrinks down to sub 100nm, it is increasingly important to monitor plasma states. Plasma etching is a key means to fine patterning of thin films. Many parameters are involved in etching and each parameter has different impact on process performances, including etch rate and profile. The uniformity of etch responses should be maintained high to improve device yield and throughput. The uniformity can be measured on any etch response. The most difficulty arises when attempting to characterize etched profile. Conventionally, the profile has been estimated by measuring the slope or angle of etched pattern. One critical drawback in this measurement is that this is unable to cap...