• 한국재료학회지
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• 제26권9호
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• pp.486-492
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• 2016

Tungsten (W) thin film was deposited at $400^{\circ}C$ using pulsed chemical vapor deposition (pulsed CVD); film was then evaluated as a nucleation layer for W-plug deposition at the contact, with an ultrahigh aspect ratio of about 14~15 (top opening diameter: 240~250 nm, bottom diameter: 98~100 nm) for dynamic random access memory. The deposition stage of pulsed CVD has four steps resulting in one deposition cycle: (1) Reaction of $WF_6$ with $SiH_4$. (2) Inert gas purge. (3) $SiH_4$ exposure without $WF_6$ supply. (4) Inert gas purge while conventional CVD consists of the continuous reaction of $WF_6$ and $SiH_4$. The pulsed CVD-W film showed better conformality at contacts compared to that of conventional CVD-W nucleation layer. It was found that resistivities of films deposited by pulsed CVD were closely related with the phases formed and with the microstructure, as characterized by the grain size. A lower contact resistance was obtained by using pulsed CVD-W film as a nucleation layer compared to that of the conventional CVD-W nucleation layer, even though the former has a higher resistivity (${\sim}100{\mu}{\Omega}-cm$) than that of the latter (${\sim}25{\mu}{\Omega}-cm$). The plan-view scanning electron microscopy images after focused ion beam milling showed that the lower contact resistance of the pulsed CVD-W based W-plug fill scheme was mainly due to its better plug filling capability.

• 한국측량학회지
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• 제24권1호
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• pp.1-8
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• 2006

효율적인 3차원 모델링은 건설, 기계 그리고 디자인과 같은 폭넓은 설계분야에서 필수적으로 되고 있다. 특히, 역설계를 가능케 하는 툴로써 발전하고 있다. 3차원 모델링은 신속성, 정확성 그리고 명확성이 요구된다. 모델링을 위한 데이터 획득은 접촉식 좌표측정기, 레이져스캐너, 패턴스캐너 그리고 수치사진측량방법을 이용한다. 본 연구에서는 모델링 기법을 분석하고 패턴스캐너를 이용한 3차원 모델링기법을 소개하고자 한다. 또한, 본 연구는 OPTO-Top 패턴스캐너를 이용하여 3차원 모델링을 시도하고 신속성과 효율성을 수치사진측량기법과 비교분석하였다. 아울러 3차원으로 사용자가 웹환경에서 시뮬레이션 할 수 있는 환경구축을 시도하였다.

• Structural Engineering and Mechanics
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• 제12권2호
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• pp.201-214
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• 2001

Four finite element (FE) models are examined to find the one that best estimates moment-rotation characteristics of top- and seat-angle with double web-angle connections. To efficiently simulate the real behavior of connections, finite element analyses are performed with following considerations: 1) all components of connection (beam, column, angles and bolts) are discretized by eight-node solid elements; 2) shapes of bolt shank, head, and nut are precisely taken into account in modeling; and 3) contact surface algorithm is applied as boundary condition. To improve accuracy in predicting moment-rotation behavior of a connection, bolt pretension is introduced before the corresponding connection moment being surcharged. The experimental results are used to investigate the applicability of FE method and to check the performance of three-parameter power model by making comparison among their moment-rotation behaviors and by assessment of deformation and stress distribution patterns at the final stage of loading. This research exposes two important features: (1) the FE method has tremendous potential for connection modeling for both monotonic and cyclic loading; and (2) the power model is able to predict moment-rotation characteristics of semi-rigid connections with acceptable accuracy.

• 마이크로전자및패키징학회지
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• 제7권2호
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• pp.47-53
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• 2000

TSM(Top Surface Metallurgy)이 증착된 유리기판의 Pb-free 솔더에 대한 젖음성을 무플럭스하에서 wetting balance법으로 평가하였다. TSM 층의 젖음성을 단면 증착시편의 wetting balance법으로부터 도출된 새로운 젖음성 지수들로 평가할 수 있었다. 유리기판의 TSM층으로는, Cu를 젖음층으로 하고 Au를 Cu의 산화 방지 층으로 사용하는 경우가 Au 자체를 젖음층으로 사용하는 경우보다 우수하였다. SnSb 솔더는 SnAg, SnBi, SnIn 솔더보다 TSM층에 대한 젖음특성이 우수하였다. 유리기판에 단면 증착된 TSM과 Pb-free솔더의 접촉각을 $F_{s}$와 기울어짐각을 측정하고, 메니스커스의 정적 상태에서 힘의 평형으로부터 유도된 식을 이용하여 계산할 수 있었다.

• 한국전기전자재료학회논문지
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• 제30권6호
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• pp.401-405
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• 2017

Because silicon thin film solar cells have a high absorption coefficient in visible light, they can absorb 90% of the solar spectrum in a $1-{\mu}m$-thick layer. Silicon thin film solar cells also have high transparency and are lightweight. Therefore, they can be used for building integrated photovoltaic (BIPV) systems. However, the contact electrode needs to be replaced for fabricating silicon thin film solar cells in BIPV systems, because most of the silicon thin film solar cells use metal electrodes that have a high reflectivity and low transmittance. In this study, we replace the conventional aluminum top electrode with a transparent aluminum-doped zinc oxide (AZO) electrode, the band level of which matches well with that of the intrinsic layer of the silicon thin film solar cell and has high transmittance. We show that the AZO effectively replaces the top metal electrode and the bottom fluorine-doped tin oxide (FTO) substrate without a noticeable degradation of the photovoltaic characteristics.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권1호
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• pp.15-21
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• 2013

In this paper, a MEMS tunable capacitor was successfully designed and fabricated using an aluminum nitride film and a gold suspended membrane with two air gap structure for commercial RF applications. Unlike conventional two-parallel-plate tunable capacitors, the proposed tunable capacitor consists of one air suspended top electrode and two fixed bottom electrodes. One fixed and the top movable electrodes form a variable capacitor, while the other one provides necessary electrostatic actuation. The fabricated tunable capacitor exhibited a capacitance tuning range of 375% at 2 GHz, exceeding the theoretical limit of conventional two-parallel-plate tunable capacitors. In case of the contact state, the maximal quality factor was approximately 25 at 1.5 GHz. The developed fabrication process is also compatible with the existing standard IC (integrated circuit) technology, which makes it suitable for on chip intelligent transceivers and radios.

• KIEAE Journal
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• 제10권1호
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• pp.25-31
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• 2010

An experimental investigation of composite beams composed of wide flange steel and precast concrete is presented. The bottom flange of the steel section is encased in precast concrete. The composite beams tested in this study were designed to reduce the depth of the slab and beam. The slabs are constructed on top of the edges of the Structural Composite Hybrid System, instead of on top of the steel flange, decreasing the depth of the beams. When concrete is cast on the metal deck plate located on the edges of the precast concrete, the weight of the concrete slabs and other construction loads must be supported by the contacts between the steel and the precast concrete. This interface must not exhibit bearing failures, shear failures, and failures caused by torque due to the loading of the precast concrete. When the contact area between the concrete and the bottom flange of the steel beam is small, these failures of the concrete are likely and must be prevented. The premature failure of precast concrete must not also be present when the weight of the concrete slabs and other construction loads is loaded. This paper presents a load carrying capacity of Structural Composite Hybrid System in order to observe the failure mode. The symmetrically distributed loading that caused the failure of the composite beam was found. The paper also provides design recommendations of such type of composite structure.

• 대한가정학회지
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• 제20권4호
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• pp.13-22
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• 1982

While the women of the Korea Dynasty wore hat(笠子) and Mongsu(蒙首) on top of it when going out, the Yi Dynasty, due to more strict Contucian ethics and isolated way of life, had seen the development of the covering clothes, rather veil, for avoiding the opposite sex with diversity and both men and women began wearing PHO(coat), a Korean topcoat over the head and thurs called Changots, but originally PHO for men was named Changyi a men's outer coat. Neuwul(羅兀), like Mongsu(蒙首) of Korea Dynasty was a thin black hood worn on top of the Wowllip or a kind of skirt draped over the head and the latter was called Changots, very similar to Sgaechima, a kind of long hood formally worn by women. Meanwhile, local women wore a long veil with no arm sleeves dubbed Cheunyi(薦衣) But since western civilization and culture landed on Korea around the end of the 19th century, the women's social status has been raised to almost the same level with men and the way of life has changed towards openness, in which men and women have almost daily contact with one another, so these days we can hardly find such veil style covering clothes around us.

• The International Journal of Costume Culture
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• 제7권2호
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• pp.151-157
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• 2004

This research is to conservate the old hat and restore its shape and place it on a supportive form in a stable protective container. The hat is a homemade construction, utilizing three different machine made laces, and two cotton net fabrics. The exterior, particularly the top crown piece, as well as the lace along the brim's edge has been generally soiled and discolored. Inside the crown, the cotton net has broken threads, and thread loss in several areas. The paper covering the two wires is very weak, and has discolored the lace in the areas of contact. The plastic buckles of the velvet ribbon have also discolored the areas where there is contact. The wash/bleach bath procedure was very effective. Virtually all of the light brown surface discoloration stains were removed. The darker brown spots, particularly concentrated around the two paper covered wires and assumed to be rust, were $90\%$ removed by the treatment. The brown spots apparently were due to the degradation of the paper covering, and not caused by the wire itself. The buckram foundation lost about $50\%$ of its stiffness, but this was not a major concern due to the fact that this hat should remain it its mount, which has been designed to serve for both storage and exhibition purposes.

• Structural Engineering and Mechanics
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• 제48권4호
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• pp.479-500
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• 2013

This paper presents the experimental as well as analytical study conducted on layer-bonded scrap tire rubber pad (STRP) isolators to develop low-cost seismic isolators applicable to structures in developing countries. The STRP specimen samples were produced by stacking the STRP layers one on top of another with the application of adhesive. In unbonded application, the STRP bearings were placed between the substructure and superstructure without fastening between the contact surfaces which allows roll-off of the contact supports. The vertical compression and horizontal shear tests were conducted with varying axial loads. These results were used to compute the different mechanical properties of the STRP isolators including vertical stiffness, horizontal effective stiffness, average horizontal stiffness and effective damping ratios. The load-displacement relationships of STRP isolators obtained by experimental and finite element analysis results were found to be in close agreement. The tested STRP samples show energy dissipation capacity considerably greater than the natural rubber bearings. The layer-bonded STRP isolators serve positive incremental force resisting capacity up to the shear strain level of 150%.