• 폴리머
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• 제33권6호
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• pp.581-587
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• 2009

PLA와 PEG를 사용하여 용융블렌드 방법으로 PLA/PEG 블렌드 섬유를 제조한 후 in vitro 환경조건인 pH7.4, 온도 $37\;^{\circ}C$의 완충용액에서 1~8주 동안 가수분해한 다음 무게감량률 및 인장강도 등에 미치는 영향을 검토하였다. 가수분해 시간이 1주에서 8주까지 증가함에 따라 블렌드 시간은 10~30분으로, PEG 함량은 5~30 wt%로 증가할수록 PLA/PEG 블렌드 섬유의 무게감량률은 증가하는 경향이, 인장강도 및 인장탄성률은 감소하는 경향이 현저하게 나타남을 확인하였다. 결론적으로 가수분해 시간 2주까지는 PLA/PEG 블렌드 섬유의 무게 감량률은 약 0.9% 이내이고 강도유지율은 약 90% 이상을 나타냄으로써 임계상처치유기간 중 양호한 강도가 유지될 수 있음을 확인하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.236-250
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• 2016

Electrical Designs for Application Specific Integrated Circuits (ASIC) has undergone a change recently with the advent of the sub-wavelength lithography. The optical projection with 193 nm wavelength has been further extended with the use of immersion and other techniques. The competing trends for printing smaller design features have been discussed in this paper with the discussion of the electrical layout analysis to find unfriendly design features. The early knowledge of the unfriendly design features allows remedial actions in time for better yield on the wafer. There are existing standard design qualification criteria being used in the design and fabrication community, but they seem to be insufficient to guarantee defect free designs. This paper proposes an integrated approach for screening the layout with multiple aspects: layout geometry based, graphical analysis and process model based verification. The results have been discussed with few example design features from the 28nm design layout.

• 한국세라믹학회지
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• 제56권6호
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• pp.521-525
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• 2019

A study was conducted to investigate the possibility of a composite material containing a composite resin as a matrix and hydroxyapatite (HAp) powder as a substitute material for tooth repair. As the content of HAp increased, hardness value (111.9 HV at 9%) increased and flexural strength (73.3 MPa at 9%) decreased. Observation of the microstructure after immersion in a simulated body fluid (SBF) solution confirmed a dense structure due to mutual coagulation and curing. It was thought that fine HAp recrystals were formed with the lapse of time, and they were entangled to form a condensation structure and had a dense structure. In addition, since the activity was shown by the ion migration on the surface of a tooth, it was highly likely that a biocompatible bond occurred during tooth contact. Therefore, it could be used as a substitute material for tooth repair.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.151-154
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• 2002

The durability of two kinds of CFRP plates, carbon/UP and carbon/V, was studied under severe environmental conditions. Immersion into the chemical solutions and accelerated weathering were executed on the CFRP plates and the weight change under each condition was measured. After those treatments, the plates were tested by tensile testing machine to measure the mechanical properties and observed by SEM to find the damage behaviour of the surface. Comparing the virgin plates and the chemically exposed plates, both plates show severe deterioration of the mechanical properties. But, the plates subjected to alkali solution show much larger reduction than those of acidic solution and carbon/V has better chemical resistance than carbon/UP. The material properties of CFRP plate exposed to the weathering were deteriorated linearly proportional to the exposure time.

• 한국멀티미디어학회논문지
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• 제19권12호
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• pp.2036-2043
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• 2016

The $360^{\circ}$ Virtual Reality (VR) live-action movies are filmed by attaching multiple cameras to a rig to shoot the images omni-directionally. Especially, for a live-action film that requires a variety of scenes, the director of photography and his staff usually have to operate the rigged cameras directly all around the scene and edit the footage during the post-production stage so that the entire process can incur much time and high cost. However, it will also be possible to acquire high-quality omni-directional images with fewer staff if the camera rig(s) can be controlled remotely to allow more flexible camera walking. Thus, a $360^{\circ}$ VR filming system with remote-controlled camera rig has been proposed in this study. The movie producers will be able to produce the movies that provide greater immersion with this system.

• 한국안전학회지
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• 제17권2호
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• pp.85-91
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• 2002

A research on the performance of retrofit anchors was conducted using adhesives for rehabilitation. From the pull-out tests of the chemical anchors, the effect of the hole diameter, spacer, temperature, moisture, embedment depth, and aging time were investigated. The spacer did not directly increased the pull-out load hilt increased post-yielding resistance therefore the ductility of the retrofit anchors. When the hole was cleaned and dried after the immersion, the pull-out load was greatly increased compared to the wet hole. A design equation was unposed depending on the embedment depth of the anchor bolt.

• 한국농공학회논문집
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• 제53권5호
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• pp.17-23
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• 2011

Steel clapping plate is used to connecting rubber body in rubber dam. However, once the steel clapping plate corrodes, it may cause faults, such as the same problems experienced by typical reinforcing steel. This study evaluated the applicability of glass fiber reinforced polymer composite(GFRP) clapping plate as a substitute for steel clapping plate. Absorption and load test were conducted to evaluate the decrease in durability of GFRP clapping plate exposed to deterioration environments. In the durability test results, the absorption rate of GFRP clapping plate was appeared as 0.6~1.0% in 50 day of immersion time. Also, the fracture load decreased with accelerated degradation environment exposure. Moreover, the absorption rate in GFRP clapping plate increased as degradation progressed, reducing the fracture load.

• 한국표면공학회지
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• 제29권1호
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• pp.60-72
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• 1996

A photoetching process is widely used for small and high precision parts in machinery, electronic and semi-conductor industries. One of the high precision parts, grid is very important part of digitron which use electron display, and it is fabricated by only photoetching process because of high precision. In this study, to develop high precision digitron grid, characteristics of etching solution were investigated with electrochemical test, that was potentiodynamic test and immersion test in the ferric chloride solution and added some additives. Based on the electrochemical etching test, grid was fabricated by continuous photoetching process at various etching condition. From the result of measured line width and etching depth under-cut and etching factor were calculated. For the fabrication of 25$\mu\textrm{m}$ line width, optimal etching condition was etching temperature 40~$45^{\circ}C$, spray pressure 1.5kg/$\textrm{cm}^2$ and etching time 3~4min.

• 멤브레인
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• 제15권2호
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• pp.85-104
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• 2005

Recently, membrane can be prepared by two methods, phase inversion and electrospinning techniques. Phase inversion technique is a conventional but commercially preparation membrane. The most versatile of preparation in this technique is immersion of the cast film into nonsolvent bath, causing dense top layer with a finger-like pattern in the sub layer membrane. The membrane pore size getting from phase inversion is in the range of micro or submicrometer. As a result, it can be used as microfiltration and ultrafiltration applications. A new technique, electrospinning, is introduced for membrane preparation. Nonwoven nanofibrous mat or nanofibrous membrane is obtained. In this technique, electrostatic charge is introduced to the solution jet, causing a thin fiber with high surface area; hence it can be used in the applications where high surface area-to-volume or length-to-diameter ratios are required. Moreover, the pore size can be controlled by controlling the time of electrospinning. Hence, it can be used as a filter for filtering microparticles as well as nanoparticles.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.577-580
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• 2006

As this study is to estimate resistance of cement mortars using crushed sand under chemical attacks. Besides tests have been carried out with cement mortars by river sand and crushed sand by fine sand, cement mortars mix various proportions of silica fume and fly ash(up to 15% and 50% by weight for cement) were prepared and immersed in pure water, sodium sulfate solution, magnesium sulfate solution, seawater for 28days, 60days, 90days and 180days. Test on the change in the weight and compressive strength of cement mortars according to the duration of immersion time and the content of silica fume and fly ash was performed.