• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.456-456
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• 2010

CMOS 소자가 서브마이크론($0.1\;{\mu}m$) 이하로 스케일다운 되면서 단채널 효과(short channel effect), 게이트 산화막(gate oxide)의 누설전류(leakage current)의 증가와 높은 직렬저항(series resistance) 등의 문제가 발생한다. CMOS 소자의 구동전류(drive current)를 높이고, 단채널 효과를 줄이기 위한 가장 효율적인 방법은 소스 및 드레인의 얕은 접합(shallow junction) 형성과 직렬 저항을 줄이는 것이다. 플라즈마 도핑 방법은 플라즈마 밀도 컨트롤, 주입 바이어스 전압 조절 등을 통해 저 에너지 이온주입법보다 기판 손상 및 표면 결함의 생성을 억제하면서 고농도로 얕은 접합을 형성할 수 있다. 그리고 얕은 접합을 형성하기 위해 주입된 불순물의 활성화와 확산을 위해 후속 열처리 공정은 높은 온도에서 짧은 시간 열처리하여 불순물 물질의 활성화를 높여주면서 열처리로 인한 접합 깊이를 얕게 해야 한다. 그러나 접합의 깊이가 줄어듦에 따라서 소스 및 드레인의 표면 저항(sheet resistance)과 접촉저항(contact resistance)이 급격하게 증가하는 문제점이 있다. 이러한 표면저항과 접촉저항을 줄이기 위한 방안으로 실리사이드 박막(silicide thin film)을 형성하는 방법이 사용되고 있다. 본 논문에서는 (100) p-type 웨이퍼 He(90 %) 가스로 희석된 $PH_3$(10 %) 가스를 사용하여 플라즈마 도핑을 실시하였다. 10 mTorr의 압력에서 200 W RF 파워를 인가하여 플라즈마를 생성하였고 도핑은 바이어스 전압 -1 kV에서 60 초 동안 실시하였다. 얕은 접합을 형성하기 위한 불순물의 활성화는 ArF(193 nm) excimer laser를 통해 $460\;mJ/cm^2$의 에니지로 열처리를 실시하였다. 그리고 낮은 접촉비저항과 표면저항을 얻기 위해 metal sputter를 통해 TiN/Ti를 $800/400\;{\AA}$ 증착하고 metal RTP를 사용하여 실리사이드 형성 온도를 $650{\sim}800^{\circ}C$까지 60 초 동안 열처리를 실시하여 $TiSi_2$ 박막을 형성하였다. 그리고 $TiSi_2$의 두께를 측정하기 위해 TEM(Transmission Electron Microscopy)을 측정하였다. 화학적 결합상태를 분석하기 위해 XPS(X-ray photoelectronic)와 XRD(X-ray diffraction)를 측정하였다. 접촉비저항, 접촉저항과 표면저항을 분석하기 위해 TLM(Transfer Length Method) 패턴을 제작하여 I-V 특성을 측정하였다. TEM 측정결과 $TiSi_2$의 두께는 약 $580{\AA}$ 정도이고 morphology는 안정적이고 실리사이드 집괴 현상은 발견되지 않았다. XPS와 XRD 분석결과 실리사이드 형성 온도가 $700^{\circ}C$에서 C54 형태의 $TiSi_2$ 박막이 형성되었고 가장 낮은 접촉비저항과 접촉저항 값을 가진다.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.3
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• pp.38-45
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• 1998

Soil and water contamination caused by the abundant use of agricultural chemicals including herbicides and fertilizers draws public concerns since these chemicals may pollute the agricultural lands as well as the food products grown on these lands. As a method to reduce the use of agricultural chemicals mulching with thin plastic film has been commonly practised for many years. Although use of the plastic film for mulching is very effective in preventing the growth of weed, it is almost impossible to remove all of the plastic film from the agricultural land and the remaining film eventually contaminates the soils. Therefore, it is very imperative to develop a mulching material that decomposes completely to prevent soil pollution problems and to enhance the competitive edge of domestic agriculture. Mulch papers are believed to have many positive characteristics in preventing problems caused by the plastic mulch film since it decomposes completely after use. However, the basis weight of mulch papers needs to be reduced to improve its handling properties and to reduce the raw material costs of pulps. In this paper the possibilities of using domestic old corrugated containers in producing mulch papers were examined. Also use of unbleached softwood kraft pulps and dry strength additives were exploited along with two-layered sheet forming technology in decreasing the basis weight of the mulch paper. Results showed that reduction of 20g/$m^2$ of basis weight of mulch paper was possible by the appropriate raw material selection and application of strength resin. To use the mulch papers in paddy fields, however, further research to improve its durability should be pursued.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.492-498
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• 2021

This feasibility study evaluated an optically transparent planar antenna using liquid salt-water as the conducting material. The most significant reason behind using liquid salt-water for transparent antenna applications is its excellent average optical transparency (OTav) (> 95% at a salinity of 40 ppt) compared to other typical solid transparent thin-film electrodes, such as indium tin oxide (ITO:> 73%) or multi-layer films (MLF: > 78%). Each conductive arm of the proposed dipole is constructed from a salt-water layer held between two clear planar acrylic layers (��r = 2.61, tan�� = 0.01, OTav > 90%) (acrylic/salt-water/acrylic; ASA) due to surface tension. To examine the electrical and optical properties of the ASA structure, the surface tension was measured to determine the thickness of the salt-water layer that finalized its sheet resistance and OTav. The average gain and efficiency of the antenna were 1.72 dBi and 74%, respectively, in the operating UHF (Ultra high frequency) band (470-771 MHz). Therefore, the proposed antenna can be a good candidate for applications as a transparent planar antenna using salt-water.

• Clean Technology
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• v.28 no.4
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• pp.323-330
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• 2022

Microfluidic paper-based analytical devices (μPADs) have recently been in the spotlight for their applicability in point-of-care diagnostics and environmental material detection. This study presents a double-sided printing method for fabricating 3D-μPADs, providing simple and cost effective metal ion detection. The design of the 3D-μPAD was made into an acryl stamp by laser cutting and then coating it with a thin layer of PDMS using the spin-coating method. This fabricated stamp was used to form the 3D structure of the hydrophobic barrier through a double-sided contact printing method. The fabrication of the 3D hydrophobic barrier within a single sheet was optimized by controlling the spin-coating rate, reagent ratio and contacting time. The optimal conditions were found by analyzing the area change of the PDMS hydrophobic barrier and hydrophilic channel using ink with chromatography paper. Using the fabricated 3D-μPAD under optimized conditions, Ni²⁺, Cu²⁺, Hg²⁺, and pH were detected at different concentrations and displayed with color intensity in grayscale for quantitative analysis using ImageJ. This study demonstrated that a 3D-μPAD biosensor can be applied to detect metal ions without special analysis equipment. This 3D-μPAD provides a highly portable and rapid on-site monitoring platform for detecting multiple heavy metal ions with extremely high repeatability, which is useful for resource-limited areas and developing countries.

• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.243-256
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• 2018

The purpose of this study was to investigate the effects of the anodization and cyclic calcification treatment on the surface characteristic and bioactivity of the titanium thin sheet in order to obtain basic data for the production of bioactive titanium membrane. A $30{\times}20{\times}0.08mm$ titanium sheets were prepared, and then they were pickled for 10 seconds in the solution which was mixed with $HNO_3:HF:H_2O$ in a ratio of 12: 7: 81. The $TiO_2$ nanotube layer was formed to increase the specific surface area of the titanium, and then the cyclic calcification treatment was performed to induce precipitation of hydroxiapatite by improvement of the bioactivity. The corrosion resistance test, wettability test and immersion test in simulated body solution were conducted to investigate the effect of these surface treatments. The nanotubes formed by the anodization treatment have a dense structure in which small diameter tubes are formed between relatively large diameter tubes, and their inside was hollow and the outer walls were coupled to each other. The hydroxyapatite precipitates were well combined on the nanotubes by the penetration into the nanotube layer by successive cyclic calcification treatment, and the precipitation of hydroxyapatite tended to increase proportionally after immersion in simulated body solution as the number of cycles increased. In conclusion, it was confirmed that induction of precipitation of hydroxyapatite by cyclic calcification treatment after forming the nanotube $TiO_2$ nanotube layer on the surface of the titanium membrane can contribute to improvement of bioactivity.

• The Korean Journal of Petroleum Geology
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• v.14 no.1
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• pp.1-11
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• 2008

As conventional oil and gas reservoirs become depleted, interests for oil sands has rapidly increased in the last decade. Oil sands are mixture of bitumen, water, and host sediments of sand and clay. Most oil sand is unconsolidated sand that is held together by bitumen. Bitumen has hydrocarbon in situ viscosity of >10,000 centipoises (cP) at reservoir condition and has API gravity between $8-14^{\circ}$. The largest oil sand deposits are in Alberta and Saskatchewan, Canada. The reverves are approximated at 1.7 trillion barrels of initial oil-in-place and 173 billion barrels of remaining established reserves. Alberta has a number of oil sands deposits which are grouped into three oil sand development areas - the Athabasca, Cold Lake, and Peace River, with the largest current bitumen production from Athabasca. Principal oil sands deposits consist of the McMurray Fm and Wabiskaw Mbr in Athabasca area, the Gething and Bluesky formations in Peace River area, and relatively thin multi-reservoir deposits of McMurray, Clearwater, and Grand Rapid formations in Cold Lake area. The reservoir sediments were deposited in the foreland basin (Western Canada Sedimentary Basin) formed by collision between the Pacific and North America plates and the subsequent thrusting movements in the Mesozoic. The deposits are underlain by basement rocks of Paleozoic carbonates with highly variable topography. The oil sands deposits were formed during the Early Cretaceous transgression which occurred along the Cretaceous Interior Seaway in North America. The oil-sands-hosting McMurray and Wabiskaw deposits in the Athabasca area consist of the lower fluvial and the upper estuarine-offshore sediments, reflecting the broad and overall transgression. The deposits are characterized by facies heterogeneity of channelized reservoir sands and non-reservoir muds. Main reservoir bodies of the McMurray Formation are fluvial and estuarine channel-point bar complexes which are interbedded with fine-grained deposits formed in floodplain, tidal flat, and estuarine bay. The Wabiskaw deposits (basal member of the Clearwater Formation) commonly comprise sheet-shaped offshore muds and sands, but occasionally show deep-incision into the McMurray deposits, forming channelized reservoir sand bodies of oil sands. In Canada, bitumen of oil sands deposits is produced by surface mining or in-situ thermal recovery processes. Bitumen sands recovered by surface mining are changed into synthetic crude oil through extraction and upgrading processes. On the other hand, bitumen produced by in-situ thermal recovery is transported to refinery only through bitumen blending process. The in-situ thermal recovery technology is represented by Steam-Assisted Gravity Drainage and Cyclic Steam Stimulation. These technologies are based on steam injection into bitumen sand reservoirs for increase in reservoir in-situ temperature and in bitumen mobility. In oil sands reservoirs, efficiency for steam propagation is controlled mainly by reservoir geology. Accordingly, understanding of geological factors and characteristics of oil sands reservoir deposits is prerequisite for well-designed development planning and effective bitumen production. As significant geological factors and characteristics in oil sands reservoir deposits, this study suggests (1) pay of bitumen sands and connectivity, (2) bitumen content and saturation, (3) geologic structure, (4) distribution of mud baffles and plugs, (5) thickness and lateral continuity of mud interbeds, (6) distribution of water-saturated sands, (7) distribution of gas-saturated sands, (8) direction of lateral accretion of point bar, (9) distribution of diagenetic layers and nodules, and (10) texture and fabric change within reservoir sand body.